PF Semester 2 Proctor Objectives

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Convert numbers into equivalent units in different value systems (metric system and household measures)

1 quart ( qt) = 2 pints ( pt) 1 pint ( pt) = 2 measuring cups 1 measuring cup = 8 ounces ( oz) 1 glass ( usually) = 8 ounces ( oz) 1 ounce ( oz) = 2 tablespoons ( T) 1 tablespoon ( T) = 3 teaspoons ( t) 1 pound ( lb) = 16 ounces ( oz) 1 foot ( ft) = 12 inches ( in) 5 milliliters ( mL) = 1 teaspoon ( t) 15 milliliters ( mL) = 1 tablespoon ( T) 30 milliliters ( mL) = 1 ounce ( oz) 240 milliliters ( mL) = 1 cup 500 milliliters ( mL) = 1 pint ( pt) 1,000 milliliters ( mL) = 1 quart ( qt) 1 kilogram ( kg) = 2.2 pounds ( lb) 2.5 centimeters ( cm) = 1 inch ( in)

Identify the parts of an x-ray machine

1. The purpose of the x-ray tube is to produce a controlled x-ray beam. 2. High kilovoltage peak (kVp) and low milliamperage-second (mAs) techniques should be used as often as possible to prevent damage to the anode. 3. X-ray tube failure is usually a result of technical error; x-ray tubes should be cared for properly. 4. The electrical components of the x-ray machine consist of (1) the transformer, (2) the generator, (3) the line-voltage compensator, (4) the timer, and (5) the rectiﬁer. The x-ray tube consists of a cathode side (with a negative electrical charge) and an anode side (with a positive electrical charge) encased in a glass envelope, which is evacuated to form a vacuum. In the tube, a stream of fast-moving electrons is produced at the cathode and directed to the anode. As the electrons collide and interact with the atoms of the target on the anode, a great amount of energy is produced; 1% of this energy is in the form of roentgen radiation (x-rays), and 99% is released as heat. A thin window area, located on the dependent portion of the tube, acts as a doorway for the exit of the x-rays. The entire tube is encased in a metal housing to prevent the escape of stray radiation and to protect the glass envelope from physical damage. The purpose of the cathode is to provide a source of electrons and direct these electrons toward the anode.The cathode consists of a coiled wire ﬁlament that emits electrons when heated. The ﬁlament in most x-ray tubes measures approximately 0.2 cm in diameter and 1 cm in length. The basic construction of the anode consists of a beveledtarget placed on a cylindric base. The target is composed of tungsten, which can withstand and dissipate high temperatures. The base of the target usually is made of copper. Copper acts as a conductor of heat and draws the heat away from the tungsten target. Each x-ray apparatus consists of more than the x-ray tube. The x-ray machine comprises many complex mechanisms that allow the radiographer to produce quality radiographs consistently and accurately. The ﬁlament in the cathode must be heated. Once it is heated and an electron cloud is available, a source of power to push the cloud toward the anode target area is necessary. These two events must not only occur but also be controlled. Transformers, timers, and generators are necessary to control the power, time, and amount of release from the x-ray beam. High-Voltage Circuit. The purpose of the high-voltage circuit is to provide the high electrical potential necessary to transport the electron stream from the cathode to the anode. The high-voltage circuit comprises two transformers: the autotransformer and the step-up transformer. Low-Voltage (Filament) Circuit. The purpose of the ﬁlament circuit is to provide the electricity (amperage) necessary to heat the ﬁlament. The amount of heat at the ﬁlament determines how many electrons are available to travel toward the anode. Timer Switch. A mechanism is necessary to control the amount of time during which high voltage is applied across the x-ray tube. The duration of x-ray generation is controlled by controlling the time of high-voltage transfer. The device used to control the length of exposure is the timer switch. Rectiﬁcation is the process of changing an alternating current to a direct current. The x-ray tube may perform its own rectiﬁcation, known as half-wave rectiﬁcation. Most modern table-based x-ray machines have a three-phase generator, which produces an almost constant electrical potential difference between the anode and the cathode. This almost constant electrical current is produced by superimposing three single-phase currents so that they are 120 degrees out of phase. In other words, each phase is 120 degrees behind the next with no deep valleys between the electrical pulses. A collimator is a restricting device used to control the size of the primary x-ray beam. The beam emerges from the x-ray tube in a diverging manner. If uncontrolled, the beam could extend to considerable width. Most x-ray machines incorporate some type of x-ray beam restriction to limit the beam to the essential size. Collimation prevents unnecessary irradiation of the patient or persons involved in restraining the patient and reduces scatter radiation. The tube stand is the apparatus that supports the x-ray tube during radiographic procedures. The design of the stand varies immensely, differing in forms of suspension. The control panel, or console, consists of the many knobs and switches necessary to operate the x-ray machine. The radiographer must be familiar with all components on the face of the panel and understand that not all control panels are alike

Calculate flow rates for IV medications and fluid therapy

A ﬂow rate implies a volume of a substance delivered over time in which the substance being delivered is the numerator of the fraction and time is the denominator. In veterinary medicine the two most common ﬂow rates are mL of i.v. ﬂuids per hour (mL/h) and L of oxygen per minute (L/min) during anesthesia. Rates can be described in more than one way. Intravenous ﬂuid rates can be described as mL/h, mL/min or mL/24 h (i.e. volume delivered in one day). We can also describe i.v. ﬂuid rates based on the weight of the patient - mL/kg/unit of time. An example would be an order to provide an i.v. ﬂuid rate during surgery of 10 mL/kg/h. In other words, for every kg of body weight, 10 mL of ﬂuid must be delivered every hour. In this rate, the denominator of the equation has a combined unit of kg-h.

Use your judgment in deciding what route of drug administration is best for a particular patient with a particular disease

A veterinarian initiates administration of drugs for therapeutic purposes. (It is unlawful for a veterinary technician to prescribe drugs for an animal patient.) The role of the technician is to administer drugs to the patient on the order of a veterinarian. When doing this, a technician must always follow the ﬁve rights: 1. Right patient 2. Right drug—check label three times before administering the drug 3. Right dose 4. Right route 5. Right time and frequency By following these rules, a technician will efﬁciently and effectively medicate a patient. Pharmaceutic companies manufacture drugs in various forms. Some drugs are available in a variety of forms; others may be available for administration in only one form. Most pharmaceutic companies endeavor to provide comfort to the patient and to ensure ease of administration when formulating their drugs. Some common drug preparations may be administered orally, parenterally, through inhalation, intrarectally, and topically. The most common type of preparation is an oral medication. Oral preparations are usually easy to administer, have extended expiration dates, and are manufactured uniformly with respect to the content of the drug. Tablets are the most commonly used oral form. A tablet may be scored or unscored. A scored tablet has indentions that have been made into its surface, allowing it to be broken into halves or quarters. Therefore, a scored tablet provides a way of administering a smaller dose to the patient. A tablet that is unscored may be cut into a smaller size with the use of a pill cutter device. However, scored tablets break more readily and are less likely to fragment. Some tablets whose drug type may be irritating to the gastrointestinal tract may be enteric-coated. Capsules are containers that house medication. The capsule itself may be made of gelatin and glycerin. The contents of a capsule may be in powder or liquid form. Capsules may be advantageous to use because they allow a patient to be treated without an unpalatable taste coming into contact with the oral mucosa. Unfortunately, capsules cannot be broken down the way a scored tablet can to provide a smaller dose. Boluses are large rectangular tablets that may be scored or unscored. Boluses are used in the treatment of large animals (e.g., cattle, horses, sheep). Boluses usually are administered to bovines with the aid of a special instrument called a balling gun. Liquid preparations for oral administration may be purchased in several different forms (e.g., mixtures, emulsions, syrups, elixirs). Mixtures consist of aqueous solutions (i.e., water) and suspensions for oral administration. A suspension usually separates after long periods of shelf life and must be shaken well before it is used, to provide a uniform dose. Syrups often are used as cough remedies; they contain the drug and a ﬂavoring in a concentrated solution of sugar water or other aqueous liquid. In veterinary medicine, an antitussive (e.g., Torbugesic) may be mixed with a liquid vitamin (e.g., Lixotinic) to ensure a more palatable taste for the patient. Elixirs usually consist of a hydroalcoholic liquid that contains sweeteners, ﬂavoring, and a medicinal agent. Emulsions consist of oily substances dispersed in an aqueous medium with an additive that stabilizes the mixture. All liquid oral medications should be administered slowly to allow the patient to swallow before more liquid is given. Rapid administration of oral medication can result in aspiration into the lungs, thereby causing pulmonary problems. Two forms of parenteral injection that are available are injections and implants. Injections are available as single-dose vials, multidose vials, ampules, or large-volume bottles, which may be used to administer intravenous infusions. A vial is a bottle that is sealed with a rubber diaphragm. A vial may contain a single dose or multiple doses. A single-dose vial must be discarded after one use (dose). Multidose vials usually contain preservatives that enable them to have a longer shelf life; thus they may be used for more than one dose. Ampules contain a single dose of medication in a small glass container with a thin neck, which is usually scored so that it can be snapped off easily. Some drugs may be unstable in solution and may require reconstitution with sterile water or another diluent; these may be used immediately for injection. Syringes and needles are used for parenteral administration of drugs. This equipment must be sterile. Drugs should never be stored in syringes for a long time before administration occurs because some drugs may be absorbed into the plastic makeup of the syringe, resulting in an inadequate dose. Implants are very hard sterile pellets that contain a chemical or a hormonal agent. Implants are inserted subcutaneously and are absorbed by the body over an extended time. Growth hormones are commonly manufactured in this form for use in cattle and are implanted in the subcutaneous dorsal aspect of the ear. Topical medications are available in several forms. Liniments are medicinal preparations for use on the skin as a counterirritant or to relieve pain. Lotions are liquid suspensions or solutions with soothing substances that may be applied to the skin. An ointment is a semisolid preparation of oil and water, plus a medicinal agent. The water in an ointment evaporates after application and leaves the drug behind on the skin's surface. Dusting powders (e.g., ﬂea powder) are mixtures of drugs in powder form for topical application. Additionally, powders may have adsorbent (corn starch) or lubricant (talcum) properties. Aerosols are drugs that have been incorporated into a suitable solvent and packaged under pressure with a propellant. Dusting powders and aerosols are common forms for some topical insecticides and wound dressings. Microencapsulation is a drug form that stabilizes substances commonly considered unstable. Microencapsulation also may be used for drugs intended to be released slowly over a period of time (e.g., moxidectin [ProHeart injection]). When the drug's active ingredients are microencapsulated, a protective environment is formed against harmful substances and the stability of the product is improved. Microencapsulation completely masks the ﬂavor of a drug and allows oral treatments to be administered with greater ease because the patient is unable to taste or smell the ingredients.

Identify the four senses whose primary function is to provide animals with an awareness of their environment and assist them in their survival

At the heart of all sense organs are various kinds of specially modiﬁed nerve endings (dendrites), called sensory receptors. When triggered by an appropriate stimulus, a sensory receptor generates a nerve impulse that travels to the CNS and is interpreted as a particular sensation. The sensory receptors of common domestic animals are sensitive to the following four general types of stimuli: 1. Mechanical stimuli (e.g., touch, hearing, balance) 2. Thermal stimuli (e.g., hot and cold) 3. Electromagnetic stimuli (e.g., vision) 4. Chemical stimuli (e.g., taste and smell)

Describe how drugs affect the nervous system

Autonomic drugs bring about their effects by inﬂuencing the sequence of events that involve neurotransmitters. Most autonomic drugs bring about this alteration of events by doing the following: 1. Mimicking neurotransmitters 2. Interfering with neurotransmitter release 3. Blocking the attachment of neurotransmitters to receptors 4. Interfering with the breakdown or reuptake of neurotransmitters at the synapse. CNS drugs have various uses in veterinary medicine. Depressant drugs are used to tranquilize or sedate animals to facilitate restraint or anesthetic procedures. They are also used to control pain, to induce anesthesia, and to prevent or control seizures. CNS drugs are also available to antagonize (reverse) the effects of some depressant drugs. Another group of CNS agents is used to stimulate the CNS to treat cardiac or respiratory depression or arrest. Euthanasia drugs allow veterinarians to provide a quick and painless end to hopeless medical situations. Drugs that affect the CNS generally cause depression or stimulation. They are thought to generate these changes by altering nerve impulse transmissions between the spinal cord and the brain or within the brain itself. Altering impulse transmissions within the thalamus could prevent messages regarding painful stimuli from reaching interpretation centers within the cerebrum. Interfering with impulses within the reticular activating system could alter levels of consciousness or wakefulness. The changes that occur in the transmission of nerve impulses as a result of administration of CNS drugs are probably brought about by altered neurotransmitter activity. The categories of CNS drugs that are covered in this chapter include the following: 1. Tranquilizers 2. Barbiturates 3. Dissociatives 4. Opioid/antagonists 5. Neuroleptanalgesics/antagonists 6. Drugs to prevent or control seizures 7. Inhalants 8. Miscellaneous CNS drugs 9. CNS stimulants 10. Euthanasia agents. The primary medical use of the CNS stimulants is or treatment of respiratory depression or arrest. Many of the other uses of CNS stimulants are illegal or unethical (e.g., to enhance athletic performance). The use of drugs to treat behavioral problems in animals is a relatively new but rapidly growing area of veterinary medicine. Behavior problems—such as separation anxiety, fears and phobias, unruliness, hyperactivity, compulsive disorders, cognitive dysfunction in older dogs, and inappropriate elimination in cats—are being diagnosed in increasing numbers. Many animals with behavioral disorders are taken in desperation to animal shelters, but a growing number of clients are willing to attempt to correct these conditions with environmental management, behavior modiﬁcation, and/or pharmacotherapy. Informed consent should be obtained from the client before these drugs are used because many of the drugs used in behavioral pharmacotherapy are human psychiatric drugs that have not been approved for use in animals. The technician or veterinarian should explain to the animal owner the extralabel status of the drug, its possible side effects or precautions, and the medical effects to be expected in the pet. Owners should also be aware that pharmacotherapy may not be a cure-all for problems of behavior, and that these problems may return after therapy is discontinued. All drugs used in psychotherapy are thought to produce their effects through alteration of neurotransmitter activity in the brain. The ﬁve neurotransmitters of clinical importance in behavioral pharmacotherapy are acetylcholine, dopamine, norepinephrine, serotonin, and GABA.

Perform mathematical manipulation of fractions and decimals

Converting mixed numbers to improper fractions makes it easier for us to work with fractions. This conversion involves two steps: ● Multiply the denominator by the whole number ● Add the numerator. The denominator stays the same. Reducing a fraction to the lowest terms is also known as simplifying a fraction. This means converting a fraction to produce the smallest numbers possible in the numerator and denominator. This is accomplished by dividing the numerator and denominator by the largest common number possible. There are times when we need to make different fractions look similar so that we can work with them. This is called ﬁnding the common denominator. This is most easily done by multiplying all the denominators in a set of fractions. The lowest common denominator (LCD) is the smallest number that is a multiple of all the denominators in a set of fractions. To add fractions: 1. First ﬁnd the LCD 2. Express each fraction using the LCD 3. Add the numerators 4. Convert to a mixed number if necessary. To subtract fractions: 1. First ﬁnd the LCD 2. Express each fraction using the LCD 3. Subtract the numerators 4. Convert to a mixed number if necessary. Unlike adding and subtracting, we do not need to ﬁnd the lowest common denominator when multiplying or dividing fractions. The numerator of one fraction is multiplied by the numerator of the second fraction and the denominator of the ﬁrst is multiplied by the denominator of the second. As in multiplication, we can divide fractions without worrying about converting them to their LCD. To divide fractions, simply invert the divisor (the number doing the dividing) and multiply.

Identify examples of respiratory drugs

It is important that a speciﬁc diagnosis be made through radiology, cytology, or appropriate culture before treatment of respiratory disease is initiated because the correct treatment for one type of disease may be contraindicated for another. Once the diagnosis has been made, treatment for respiratory disease is divided into the following three general goals: 1. Control of secretions: Secretions may be reduced by decreasing their production or increasing their elimination. Removing the cause of the secretions by means of antibiotic, antifungal, antiparasitic, or other appropriate therapy is of vital concern. Methods are also aimed at making the secretions less viscid through the use of expectorants or through nebulization of mucolytics (aerosol therapy). 2. Control of reﬂexes: Coughing may be suppressed through the use of antitussives or bronchodilators if the cough is nonproductive. Sneezing is controlled by removal of the offending agent or through the use of vasoconstrictors. Bronchospasms may be controlled with bronchodilators and corticosteroids. 3. Maintaining normal airﬂow to the alveoli: Air-ﬂow to the alveoli may be maintained by reversing bronchoconstriction, by removing edema or mucus from alveoli and air passages, and by providing oxygen therapy. Intermittent positive-pressure ventilation and other ventilation strategies are often used in humans and may have application in selected animal cases. INHALATION THERAPY FOR RESPIRATORY DISEASE Although drugs used to treat respiratory disease are often administered by the oral or parenteral route, inhalant therapy may also be useful. Aerosolization (nebulization) of drugs allows their delivery at high concentrations directly into the airways while minimizing their blood levels—a feature that may reduce the chance of toxic reaction. The efﬁcacy of an inhaled drug depends on the dose and on how well it is distributed in the lungs. Distribution of an aerosol depends on several factors such as the size, shape, and pattern of the airways and the breathing pattern of the animal. The size of the inhaled particle plays a signiﬁcant role in its distribution. The optimum particle size for entry into the peripheral airways is 1 to 5 microns (Lavoie, 2001). Particles smaller than 0.5 micron are likely to be exhaled, and those larger than 5 microns could be deposited in the upper air-ways. Airway pathology (e.g., excessive mucus or exudate) can interfere with distribution of the drug, causing some clinicians to assert that inhalant therapy should always be accompanied by systemic treatment. Concurrent use of a bronchodilator and/or a mucolytic may be a helpful adjunct to inhalant therapy. Relatively inexpensive infant units for inhalation therapy are available for use in small animals (Opti-Chamber, Aero-Chamber) and horses (Aero-Mask). Expectorants are drugs that liquefy and dilute viscid secretions of the respiratory tract, thereby helping in evacuation of those secretions. Most expectorants are administered orally, although a few are given by inhalation or parenterally. Expectorants are thought to act directly on the mucus-secreting glands or by reducing the adhesiveness of mucus. Expectorants are indicated when a productive cough is present and are often combined with other substances, such as ammonium chloride, antihistamines, or dextromethorphan. Mucolytics, such as acetylcysteine, decrease the viscosity of respiratory secretions by altering the chemical composition of the mucus through the breakdown of chemical (disulﬁde) bonds. Acetylcysteine is the only mucolytic of clinical signiﬁcance in veterinary medicine. It is administered by nebulization for pulmonary uses. This drug is also administered orally as an antidote for acetaminophen toxicity. Antitussives are drugs that inhibit or suppress coughing. Antitussives are classiﬁed as centrally acting or peripherally acting. Centrally acting agents suppress cough by depressing the cough center in the brain, whereas peripherally acting agents depress cough receptors in the airways. Peripherally acting antitussives are seldom used in veterinary medicine because they are usually prepared as cough drops or lozenges, which are not practical to administer to animal patients. Bronchodilators Contraction of the smooth muscle ﬁbers that surround the bronchioles results in bronchoconstriction and often corresponding dyspnea. Contraction of these smooth muscle ﬁbers can result from the following three basic mechanisms: 1. Release of acetylcholine at parasympathetic nerve endings or inhibition of acetylcholinesterase. Increased acetylcholine levels also tend to increase secretions of the respiratory tract, thus reducing airﬂow and adding to the level of dyspnea. 2. Release of histamine through allergic or inﬂammatory mechanisms. Histamine combines with H1 receptors on smooth muscle ﬁbers to cause bronchoconstriction. Histamine also increases the inﬂammatory response in the airways, further leading to increased levels of secretion and viscosity. 3. Blockade of beta-2-adrenergic receptors by drugs such as propranolol results in bronchoconstriction. Stimulation of beta-2-adrenergic receptors, however, produces bronchodilation. Decongestants are drugs that reduce the congestion of nasal membranes by reducing associated swelling. Decongestants may be administered as a spray or as nose drops or may be given orally as a liquid or as a tablet. These drugs act directly or indirectly (Williams and Baer, 1990) to reduce congestion through vasoconstriction of nasal blood vessels. These products have limited use in veterinary medicine but may be used to treat selected feline upper respiratory tract disease. Many human label decongestants are available. Those that are given orally and act systemically include ephedrine (Primatene), pseudoephedrine (Sudafed), and phenylpropanolamine (Ornade). Topically applied decongestants include oxymetazoline (Afrin) and phenylephrine (Neo-Synephrine). Antihistamines are substances that are used to block the effects of histamine. Histamine is released from mast cells by the allergic response and combines with H1 receptors on bronchiole smooth muscle to cause bronchoconstriction. Antihistamines may be useful in treating respiratory disease because they prevent mast cell degranulation and block H1 receptors on smooth muscle. Antihistamines are thought to be more effective when used preventively because they apparently do not replace histamine that has already combined with receptors. Respiratory conditions that may be treated with antihistamines include "heaves" in horses, pneumonia in cattle, feline asthma, and insect bites. Generic names for antihistamines often are easily recognized because most end in the sufﬁx "-amine" (e.g., pyrilamine, diphenhydramine, chlorpheniramine). Corticosteroids are used primarily in the treatment of allergic respiratory conditions. They are considered the most effective drugs in the treatment of equine chronic obstructive pulmonary disease. Corticosteroids prepared for inhalation therapy have strong antiinﬂammatory effects locally in the lungs and are rapidly biodegraded when absorbed into the general circulation. Oral corticosteroids (prednisone or prednisolone) are considered the drugs of choice in the treatment of chronic airway inﬂammation in dogs and cats. Corticosteroid therapy controls the signs of respiratory disease, not the cause; good short-term effects often ensue with few residual effects that may require long-term use.

Discuss the procedure for developing radiographs

Manual-Processing Procedure The manual-processing procedure (by hand) should be standardized as much as possible. By establishing a routine and following it, mistakes made in the darkroom are less likely. Normally, the developing tanks are positioned so that the processing procedure starts at the left and ends at the right. In other words, the developing tank is on the left, the wash tank in the center, and the ﬁx tank on the right. Manual processing is not a difﬁcult procedure, and the technique can be learned in a relatively short period. Step 1—Preparation. Before the ﬁlm is processed manually, the chemicals should be at the proper temperature (normally 20° C [68° F]) and should be stirred. Because the chemicals are suspensions, they tend to settle to the bottom of the tanks. The paddles used to stir should not be shared between tanks; the developer paddle should never go into the ﬁx tank and vice versa. (Note: Even slight ﬁxer contamination in the developer can render it useless.) At this point, the white lights should be turned off and the safelight turned on. Step 2—Unloading the cassette. Care should be taken when removing the ﬁlm from the cassette. Fingernails should not be used as a tool to remove the ﬁlm from the cassette corners. This technique can damage the sensitive intensifying screens. The proper method of removing them is to open the backplane of the cassette and gently shake the top so that the ﬁlm can be grasped by the corner between the thumb and the foreﬁnger. The x-ray ﬁlm should be handled by the corners or edges only. The cassette should be closed while it is being labeled and loaded onto the ﬁlm hanger. Film labeling is discussed at the end of this chapter. Step 3—Loading the ﬁlm on a hanger. A tension clip hanger is loaded by inserting the ﬁlm into the bottom, stationary clips ﬁrst, then rotating the hanger right side up and inserting the ﬁlm into the movable spring clips. The ﬁlm should be stretched so that it is taut enough to "bounce a coin on it." Taut mounting will prevent the ﬁlm from touching adjacent ﬁlms or walls in the processing tank. If a channel hanger is used, it should be held in one hand while sliding the ﬁlm into the channels with the other. All sides and corners of the ﬁlm should be checked for correct placement in a channel. Once the ﬁlm is imposition, the top hinge can be closed. Step 4—Developing the ﬁlm. The ﬁlm is immersed in the developing tank, and the hanger is agitated two or three times to remove any air bubbles from the ﬁlm surface. The lid on the developer tank is replaced, and the timer is set for the appropriate development time. At this juncture, the hands should be dried and the cassette reloaded with ﬁlm. Care should be taken in the reloading process. The replacement ﬁlm should meet all four corners of the cassette before closing so that no portion of them is compressed in the cassette seams. Step 5—Rinsing the ﬁlm. When the timer sounds, the ﬁlm should be removed from the developer rapidly to avoid excessive dripping back into the developer tank. For fast drainage, the hanger should be tilted so that the chemical carryover (spent developer) goes into the rinse or stop bath. Preventing the used developer from adding volume to the developer tank assists accurate tank replenishment. The ﬁlm is immersed in the rinse bath and agitated for 30 seconds. Step 6—Fixing the ﬁlm. After the ﬁlm has been in the rinse tank for 30 seconds, it should be drained of excess water and immersed in the ﬁx tank. The ﬁlm is agitated two to three times to remove any air bubbles on the ﬁlm surface, and the timer is set for the appropriate duration. The duration of the ﬁxation process is usually twice the clearing time and until after the ﬁlm has lost its "milky" appearance. The milky appearance refers to the unexposed silver halide crystals that remain on the ﬁlm. Once the silver is removed, the image will appear clear or transparent. After the ﬁlm has been in the ﬁx for1 minute, it may be viewed briefly to evaluate the quality of exposure and positioning. Putting the ﬁlm back into the tank after evaluation for a total of at least 10 minutes is important to allow maximum hardening of the ﬁlm surface. Step 7—Washing the ﬁlm. The ﬁlm is removed from the ﬁx quickly so that chemical carryover (spent ﬁxer) enters the wash tank. As with the developer, preventing carryover from entering the ﬁx tank allows for accurate ﬁx replenishment. The ﬁlm should wash for 20 to 30 minutes. The wash time depends on the water flow and exchange rate of the bath. The flow should have approximately eight complete changes per hour. Step 8—Optional ﬁnal rinse. If facilities permit, a wetting agent can speed the drying time and prevent water marks on the ﬁlm surface. The ﬁlm is briefly dipped in the wetting agent before drying. Step 9—Drying the ﬁlm. The ﬁlm should be dried in a dust-free area to prevent artifacts from sticking to the wet ﬁlm surface. If channel hangers are used, the ﬁlms should be removed from the hangers and hung with clips on a tension wire (similar to a clothesline).Tension clip hangers can be hung on a drying rack. The ﬁlms should be well separated and never allowed to touch each other while wet. When the ﬁlms are dry, the sharp points on the corners of those processed with tension clip hangers must be trimmed before ﬁling. Trimming the sharp points prevents scratching the emulsion of adjacent ﬁlms. The ﬁlms can now be inserted into the appropriately labeled envelope.

List which drugs are used to relieve pain and inflammation

Nonsteroidal Antiinﬂammatory Drugs NSAIDs are preferred because they have fewer side effects and they promote analgesia and fever reduction. Salicylates Aspirin, a salicylate, is also known as acetylsalicylic acid. Phenylbutazone, a pyrazolone derivative, is an NSAID that is commonly used in veterinary medicine. Flunixin Meglumine (Banamine) Flunixin is an NSAID that is labeled for use in horses and cattle. It has extralabel uses in other species. Dimethyl Sulfoxide DMSO is a clear liquid that was originally developed as a commercial solvent. It is noted for its antiinﬂammatory action and its ability to act as a carrier of other agents through the skin. Its antiinﬂammatory actions may be related to its ability to trap products associated with the inﬂammatory response. Buscopan Compositum is a product that contains butylscopolaminium bromide and metamizole sodium (dipyrone). This product is used for the management of abdominal pain associated with equine colic. Acetaminophen is an analgesic with limited antipyretic and antiinﬂammatory activities. Carprofen is a propionic acid derivative NSAID that has been approved for oral use in dogs. Carprofen has been approved for oral and injectable use in dogs and cats in Europe. Etodolac is an indole acetic acid derivative NSAID that has been labeled for use in dogs. Deracoxib is an analgesic and a nonsteroidal antiinﬂammatory agent of the coxib class. Firocoxib is an NSAID that belongs to the coxib class. Tepoxalin is a nonsteroidal antiinﬂammatory drug for oral use in dogs only. The manufacturer claims that this product is the only NSAID that blocks both arms of the arachidonic acid cascade (COX and lipoxygenase). It is manufactured as a "rapidly disintegrating" tablet that breaks down quickly upon contact with the moisture of the animal's mouth and cannot be spit out. This dosage form is designed to improve owner/animal dosage compliance. Meloxicam is a COX-2 receptor NSAID. It has antiinﬂammatory, analgesic, and antipyretic properties. Polysulfated Glycosaminoglycan (Adequan) Adequan is a semisynthetic mixture of glycosaminoglycans derived from bovine cartilage. This drug reduces degenerative changes induced by noninfectious or traumatic joint disease and promotes activity in the synovial membrane. It is available in intraarticular and intramuscular forms and is labeled for use in horses and dogs. Hyaluronate Sodium (Hyalovet) Hyalovet is a glycosaminoglycan that is labeled for intraarticular injection. It has activities similar to that of Adequan. Legend A solution of hyaluronate that may be given by intravenous or intraarticular injection for synovitis associated with osteoarthritis. Meclofenamic Acid (Arquel Granules) This NSAID is labeled for oral treatment of acute or chronic inﬂammatory disease in horses. Selenium and Vitamin E (Seletoc) Seletoc is labeled for relief of acute symptoms of arthritic conditions in dogs. Ketorolac is an NSAID with efﬁcacy similar to that of morphine. It carries a human label and may cause serious side effects. Orgotein (Palosein) Palosein is labeled for acute and chronic inﬂammatory conditions in horses and dogs. Opioids relieve pain by binding with speciﬁc receptor sites in the brain, spinal cord, and peripheral tissue. By altering neurotransmitter release, they alter nerve impulse formation and transmission at many levels within the CNS. The ultimate effect is that the opioids block or inhibit pain impulses to higher CNS centers responsible for the perception of pain. Opioid Agonists remain one of the most effective drug classes for relieving moderate to severe pain. Opioid agonists are drugs that bind with all opioid receptor sites and produce opioid effects and respiratory depression, sedation, and addiction. Opioid agonists include alfentanil, carfentanil, codeine, etorphine, fentanyl, hydromorphone, meperidine, methadone, morphine, oxymorphone, and sufentanil. Even though some of these drugs are considered more potent than morphine, morphine is still considered to be one of the most effective of the opioids. All agonists are C-II controlled substances. Opioid Agonists-Antagonists The opioid agonist-antagonist drugs bind with opioid kappa receptors but antagonize opioid mu receptors. Opioid agonists-antagonists include butorphanol (C-IV), pentazocine (C-IV), and nalbuphine. These drugs are considered effective for mild to moderate pain and have few side effects. The opioid partial agonists bind with the mu receptors but only partially activate them. Buprenorphine is the primary drug in this category. Recent studies have shown that buprenorphine may be effectively administered to cats by the sublingual/buccal route. Ketamine, alpha-2-adrenergic agents, lidocaine, benzodiazepines, and tricyclic antidepressants (Elavil) are other agents that are used frequently to modulate pain.These agents may be used alone or in combination with others. Some agents are delivered as a constant rate infusion (CRI) for the sustained control of pain. A common CRI for pain control involves the combination of morphine and ketamine (MK) or morphine, lidocaine, and ketamine (MLK). Skeletal muscle relaxants may be used as an aid in the treatment of acute inﬂammatory and traumatic conditions of muscle and the spasms that may result from these situations. They are thought to work by decreasing muscle hyperactivity without interfering with normal muscle tone. This action may be brought about by selective action on the internuncial neurons of the spinal cord. Methocarbamol (Robaxin-V) Robaxin-V is labeled for use in dogs, cats, and horses.

Describe how antiparasitic drugs work

Parasites are organisms that live off of a host by deriving nutrients and a home from its host. Ectoparasites are parasites that live ona host (ecto-means outer) and endoparasitesare parasites that live in a host (endo-means inner). Insecticides come with many different active ingredients. Pyrethrinsare generally safe for most mammals. They can quickly kill parasites but aren't active over longer periods of time. Synergists are used with pyrethrins to help increase their efficacy. Piperonyl butoxide is a common synergist. Synthetic pyrethroids are human-made pyrethrins that have similar characteristics. They quickly kill parasites, are relatively safe, and have limited residual activity. Care must be taken with pyrethroids, because some of them come in a concentrated form that can be very toxic to cats (their overuse causes muscle twitching and seizures). Chlorinated hydrocarbons, such as Lindane and Methoxychlor, were once very common, but many of them have been banned due to environmental concerns. Chlorinated hydrocarbons are considered hazardous to humans and domestic animals, so their use should be avoided. DDT is a chlorinated hydrocarbon that has been banned. Carbamatesact as cholinesterase inhibitors and shouldn't be used with other cholinesterase inhibitors. Organophosphates are also cholinesterase inhibitors that persist in the environment. Avoid use of organophosphates in dogs with seizures, and be careful to read instructions regarding their use. Formamidines, such as amitraz (Mitaban), are used to treat demodectic mange(a skin disease caused by mites) in dogs. People applying amitraz should read instructions carefully and wear protective clothing. Benzimidazolesare a common anthelmintic class whose generic drugs end with the -dazolesuffix (such as thiabendazole, febendazole, albendazole, etc). This class of drugs has minimal side effects and is used to treat a variety of parasites in both large and small animals. Don't use these products in lactating dairy cows or animals to be slaughtered. Organophosphatesare a pesticide applied to animals to control parasites in most species. Primarily used in large animals, this drug is a cholinesterase inhibitor. Its adverse effects are the ■SLUD syndrome (excessive salivation, lacrimation [tear production], urination, and defecation) ■Vomiting ■Diarrhea ■Muscle tremors ■Miosis (excessive smallness of the pupil) Avoid using organophosphates in dogs and cats. Safer alternatives exist. Atropine and 2-pam serve as antidotes. Tetrahydropyrimidines,such as pyrantel pamoate (Nemex, Strongid-T), are commonly used in both large and small animals. They have infrequent side effects. Imidazothiazoles, such as febantel and levamisole, are used in both large and small animals as well as in some exotic species. Avermectinsinclude ivermectin, moxidectin, and doramectin. Ivermectin is effective as a monthly heartworm preventative in both dogs and cats. Ivermectin can be used safely for birds and snakes, but not for tortoises. Ivermectin will treat endoparasites as well as ectoparasites (demodectic mange, sarcoptic mange, ear mites.

Identify and correct image faults

Penetration Evaluation of a Radiograph That Is Too Light When looking at a radiograph that is too light, it is understood that either the kVp or the mAs needs to be increased. The second question, concerning penetration, must be asked: Have the x-rays adequately penetrated the patient and reached the x-ray ﬁlm? On a ﬁlm with adequate penetration, the anatomic silhouettes (outlines) are visible. For example, when viewing an abdominal radiograph with adequate penetration, the outlines of the liver, spleen, kidneys, and bowel would be visible. If the penetration is inadequate, the outlines of the abdominal structures would not be visible and the radiograph would look almost completely white in some areas. Adequate penetration: Increase mAs 30% to 50% Inadequate penetration: Increase kVp 10% to 15% Penetration Evaluation of a Radiograph That Is Too Dark When a radiograph is too dark, either the kVp or the mAs must be decreased. We then need to ask whether the radiograph has appropriate penetration. When a radiograph is overexposed (too dark), the question is not whether there is adequate penetration power, but rather whether there is too much penetration power of the x-ray beam. Overpenetration of a patient is determined by looking at the contrast of the radiographic image, speciﬁcally, by looking at the bone tissue compared with the surrounding soft tissues. Remember, as a general rule, high kVp results in low contrast—a gray radiograph. If the bone tissue is gray and not much contrast exists between the bone and adjacent soft tissue, there was too much penetration of the patient. On the other hand, if the contrast is still acceptable and the bone tissue is relatively white compared with the surrounding soft tissues, it is evident that the kVp is not the problem and that the mAs should be altered. Not overpenetrated: Decrease mAs 30% to 50% Overpenetrated: Decrease kVp 10% to 15% A quality radiograph has adequate penetration, sufﬁcient density, and good contrast. These requirements differ for bone and soft tissue. To be of diagnostic value, a radiograph must have the correct scale of contrast. For soft tissue, low contrast is desirable. An abdominal radiograph, for example, should have many soft grays to assist differentiation of the intraabdominal organs. High contrast is necessary for bone radiography. The image should be well deﬁned, and the bone should be distinct from the surrounding tissue. Film too dark Overexposure due to too much kVp or mAs Overdevelopment due to too much time in developer or increased developer temperature Overmeasurement of part under examination Machine (meters or timer) out of calibration Source-image distance not correct for grid use Film too light Underexposure due to insufficient kVp or mAs Underdevelopment due to decreased temperature or time of development, developer exhausted or diluted X-ray tube failure Incorrect film-screen combination Machine timer out of calibration Drop in incoming line voltage Film gray/lack of contrast Too much kVp Radiation fog due to exposure of film to radiation other than desired exposure Light leak in darkroom Storage fog due to conditions that are too hot or too humid Chemical fog due to old chemicals, increased chemical temperature, or increased time of development Film out of date Lack of a grid with use of high kVp Double exposure Incorrect bulb wattage or filter for safelight in darkroom Lack of detail Increased object—film distance Blurring due to poor screen-film contact Blurring due to patient motion Blurring due to x-ray tube motion Distorted image due to central x-ray not directed at center of film Double exposure Heavy lines on radiograph (generalized) Grid lines due to: Grid out of focal range Grid out of alignment to x-ray central beam Grid upside down Damaged grid Roller marks as result of film jammed in automatic processor Inconsistent film density Collimation of primary beam Bucky tray not positioned directly under primary x-ray beam Cassette not locked into Bucky tray correctly Light leak into cassette Quantum mottle Target damage (pitted anode) Variable screen-film contact == Black marks (not generalized) Crimping or folding of film Two films sticking together during development Static electricity Developer on film before processing Fingerprints as a result of developer on hands while loading or unloading cassette Clear areas on film (white Hair in cassette marks; not generalized)Scratch in film emulsion Line due to scratch on screen surface Contrast medium on cassette or table Air bubble on film during developing procedure Film touching side of tank during manual processing Fingerprints due to film handling with contaminated hands Yellow radiograph Fixer splashes on film before developing Premature age due to improper fixation Film sticking together during fixing process Incomplete washing so that residual fixer oxidizes to yellow powder while destroying the image

Discuss factors that influence the radiographic image

Radiographic density is deﬁned as the degree of blackness, or "darkness," on a radiograph. Black areas on a developed radiograph are produced by deposits of metallic silver in the ﬁlm emulsion that result from exposure to x-rays and their subsequent processing. A radiograph that has many black areas and is dark when viewed has high density. An important concept to remember is that x-rays make radiographic ﬁlm black. The degree of blackness on a radiograph depends on the amount of x-rays reaching the ﬁlm. Density is influenced by the quantity and quality of the x-ray beam, as well as the type and thickness of the tissue under examination. Greater radiographic density may be produced by increasing (1) the total number of x-rays that reach the ﬁlm, (2) the penetrating power of the x-rays, (3) the developing time, or (4) the temperature of the developer. The number of x-rays leaving the x-ray tube is determined by the milliamperage-seconds (mAs). As the mAs is increased, more x-rays reach the patient and ﬁlm and radiographic density is increased. In the same respect, raising the kilovoltage (or kVp) of the x-ray beam increases radiographic density. As the kVp is increased, the penetrating power of the x-rays is increased, resulting in more x-rays reaching the ﬁlm. The radiograph becomes darker as more x-rays reach the ﬁlm. Radiographic density is also influenced by the thickness and type of tissue being radiographed. Body parts that have greater thickness absorb more x-rays, resulting in a lighter image on the radiograph. Contrast is deﬁned as the visible difference between two adjacent radiographic densities. Contrast is divided into two separate categories: radiographic contrast and subject contrast. To avoid confusion, we will deﬁne each contrast-associated term and explain how both influence the outcome of a radiograph. Radiographic contrast is the density difference between two adjacent areas on a radiograph. When the density difference is great, the radiograph is said to have high contrast or a short scale of contrast. That is, a radiograph with high contrast exhibits many black and white tones. For example, a radiograph with white bone and a black background has high contrast. Subject contrast is deﬁned as the difference in density and mass between two adjacent anatomic structures. Subject contrast depends on the thickness and density of the anatomic part. As discussed earlier, the body has various tissue densities. Because x-rays cannot penetrate bone tissue as easily as soft tissue, fewer x-rays will reach the ﬁlm where the bone is located. Bone will absorb many more x-rays than muscle or fat, assuming both have equal thickness. With appropriate exposure factors, anatomy that has high tissue density can increase the amount of whites and blacks on the radiograph; therefore high subject contrast increases radiographic contrast. The mAs may affect contrast only when insufﬁcient or excessive mAs is used. Remember, the mAs is the quantity of the x-rays and is the primary factor that affects density. When a correct mAs setting is used, contrast depends primarily on the kVp setting. However, when the mAs factor is insufﬁcient, the contrast is reduced because the overall density of the radiograph is reduced. If the quantity of x-rays reaching the ﬁlm is too low, the ﬁlm will be pale. Both contrast and density are affected by kVp. The correct amount of kVp will produce differential x-ray absorption of soft and dense anatomic structures. A change in kVp has a number of effects. An increase in kVp results in an increase in penetrating power of the x-ray beam. When the kVp is raised, shorter-wavelength x-rays are produced, which raises penetration power. As the penetration is increased, scatter radiation alters radiographic contrast. Scatter radiation is covered in more detail later. Non-image-forming radiation that is scattered in all directions as a result of objects in the path of the beam is called scatter radiation. Scatter radiation is undesirable for a number of reasons. Because inappropriate areas of the ﬁlm are being exposed, contrast is decreased. A grid is a device placed between the patient and the radiographic ﬁlm that is designed to absorb non-image-forming x-rays (scatter radiation). A grid is composed of alternating strips of lead and spacer material. Radiographic detail and deﬁnition are terms used to describe image sharpness, clarity, distinctness, and perceptibility. Detail describes the deﬁnition of the edge of an anatomic structure on a radiograph. The radiographer tries to obtain as much diagnostic information as possible about the internal structures of the patient. To achieve this goal, image clarity is essential. Lack of detail can result from several different factors.

Perform dosage calculations

Sometimes the amount of medication prescribed is based on the patient's size. A patient who is larger will receive a larger dose of the drug, and a patient who is smaller will receive a smaller dose of the drug. The size of a patient is measured by either body weight or body surface area ( BSA). In general, when the order is based on the size of the patient, if you multiply the size of the patient by the order, you will obtain the dose. In some cases, body surface area ( BSA) may be used rather than weight in determining appropriate drug dosages. This is particularly true when calculating dosages for children, those receiving cancer therapy, burn patients, and patients requiring critical care. A patient's BSA can be estimated by using formulas or nomograms.

List the components of the central nervous system

Structurally the nervous system has two main divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system is composed of the brain and spinal cord, and the peripheral nervous system consists of cordlike nerves that link the central nervous system with the rest of the body. Functionally the nervous system's activities fall into three main categories: (1) sensory functions, (2) integrating functions, and (3) motor functions. The nervous system senses changes from within the body or from outside the body and conveys this information to the spinal cord and brain. In the brain and spinal cord, the sensory information is received, analyzed, stored, and integrated to produce a response. A motor response instructs the body to do something, such as contract a muscle or cause a gland to secrete its product(s).

Explain the structure and functions of each of the components of the digestive system

The GI tract extends from the mouth through the esophagus, stomach, small intestine, and large intestine to the anus. The term gastrointestinal is synonymous with the term gastroenteric for which gastro refers to the stomach (e.g., gastric ulcer) and enteric relates to the intestines (e.g., enteritis is inﬂammation of the intestines). The digestive tract has the following basic functions: 1. Prehension (grasping) of food with the lips or teeth 2. Mastication, the mechanical grinding and breaking down of food (chewing) 3. Chemical digestion of food 4. Absorption of nutrients and water 5. Elimination of wastes. If any of these processes fails to function properly, the animal may fail to gain proper weight, may lose weight, and eventually may die from malnutrition. Therefore we need to understand each of these processes and to comprehend how alteration of any of these functions could produce diseases or clinical signs, such as diarrhea, vomiting, weight loss, or bloat (particularly in ruminants). The mouth, or oral cavity, is also called the buccal cavity. The mouth is where the food is initially taken in and where digestion actually begins. The key structures of clinical signiﬁcance in the mouth include the lips, tongue, teeth, salivary glands, hard palate, soft palate, and oropharynx. The lips may play an important role as a prehensile organ, meaning that the animal, such as the horse, can use the lips to grasp the food and pull it into the mouth. Paralysis of the lips caused by disease or trauma can result in the animal being unable to feed itself adequately. The highly sensitive nature of the lips makes them a signiﬁcant sense organ in horses, cattle, and some other species. In carnivores, the lips play a more passive role in eating. Labial is the term used to describe anything pertaining to the lips. The purpose of the oral cavity is to prehend (take hold of) the food, initiate mastication (chewing) and chemical digestion, and prepare the food for swallowing. Mastication can also be referred to as mechanical digestion. It breaks food down into smaller particles to increase the surface area available for exposure to the enzymes involved in chemical digestion. (Think about how crushed ice melts faster than a single ice cube of equivalent mass.) Digestive enzymes are proteins that promote (catalyze) the chemical reactions that split complex food molecules up into simpler compounds. (Enzymes can be recognized because their names usually end in the sufﬁx ase. They are secreted in the digestive system to break down different components of the food (sugars, proteins, and fats etc.). The addition of saliva to the food as it is chewed helps moisten, soften, and shape it into a form that is more readily swallowed. The esophagus is a muscular tube that extends from the pharynx (throat) to the stomach. Its function is to conduct swallowed material to the stomach. No signiﬁcant digestion or absorption takes place; it is a transport tube only. The esophagus enters the stomach in an area called the cardia. A weak sphincter (circular muscle capable of closing off an opening) of smooth muscle surrounds the cardia (the cardiac sphincter), and the esophagus enters the stomach at an angle. As the stomach expands with food, the fold of the stomach against the esophagus acts as a natural valve to close the lower end of the esophagus and reduce the risk for reﬂux (reﬂux is the movement of stomach contents, or ingesta, back up the esophagus). In some species, this anatomical closure can be so strong that reﬂux or vomiting is nearly impossible. The horse and rabbit are two species in which this is true. The monogastric stomach is generally divided into ﬁve different areas. The cardia is the area immediately surrounding the opening from the esophagus into the stomach. As mentioned in the section on the esophagus, the cardiac sphincter helps reduce reﬂux of stomach contents back up into the esophagus. The orientation of the esophagus as it enters the stomach also provides a natural closure for the cardia as the stomach ﬁlls and distends. The fundus is the section of the stomach that forms a distensible, blind pouch that expands as more food is swallowed. The body of the stomach is also a distensible section in the "middle" of the stomach. The fundus and body of the stomach are rich with glands. Typically, the gastric glands (gastric refers to the stomach) in this region of the stomach contain three key cells: (1) parietal cells (also called oxyntic cells in older texts), which produce the hydrochloric acid; (2) chief cells, which produce an enzyme precursor called pepsinogen; and (3) mucous cells, which produce the protective mucus. (Note that mucous is the adjective and mucus is the noun.) The pyloric antrum is the distal part of the stomach that grinds up swallowed food and regulates the hydrochloric acid that is produced by the fundic and body parietal cells. The glands of the pyloric antrum contain endocrine cells called G cells, which secrete the hormone gastrin. The presence of food stimulates the G cells to dump gastrin into the blood. It travels, among other places, to the gastric glands in the proximal part of the stomach, where it stimulates the release of hydrochloric acid from the parietal cells. Like the gastric glands in the fundus and body, the gastric glands in the pyloric antrum also contain many mucous cells. The pylorus is the muscular sphincter (ring of muscle in tubular organ) that regulates the movement of chyme (or digested stomach contents) from the stomach into the duodenum (ﬁrst part of the small intestine) and prevents backﬂow of duodenal contents into the stomach. The stomach is shaped roughly like a C lying on its side. The inside curve of the C is called the lesser curvature of the stomach, and the outside curve is called the greater curvature of the stomach. This terminology is often used in describing landmarks for surgical procedures involving the stomach and for anatomical location of organs immediately surrounding the stomach (e.g., spleen and pancreas). Ruminant animals such as cattle, sheep, and goats are often referred to incorrectly as having four (4) stomachs. They actually have only one true stomach (the abomasum), but they have three forestomachs (the reticulum, rumen, and omasum). The forestomachs are compartments of differing sizes and functions that swallowed material must pass through before reaching the abomasum. This conﬁguration is adapted to the herbivore (plant-eating) diet of ruminant animals. Ruminants, as the name implies, ruminate their food. In other words, they swallow their food and bring it back up the esophagus to their mouth (regurgitation) to chew on it some more before swallowing it again. Technically this process is called rumination. In lay terminology, this is called "chewing the cud." The smallest and most cranial compartment of the forestomach compartments of adult ruminants is the reticulum. The reticulum is separated from the rumen by the ruminoreticular fold. The lining of the reticulum has a honeycomb arrangement of folds. The four- to six-sided structures of the honeycomb serve to increase the surface area of the reticulum and thus increase the absorptive surface. The muscular wall of the reticulum is continuous with the wall of the rumen, and the two compartments contract in a coordinated manner. Therefore the motility of the rumen and reticulum is usually discussed together in what are known as reticulorumen contractions. The rumen can be thought of as a large, fermentative vat that processes plant materials into usable energy and cellular building materials for the cow. The rumen is actually a series of muscular sacs partially separated from one another by long, muscular folds of rumen wall called pillars (seen and described as grooves from the outside of the rumen). During ruminal contractions, these pillars can almost close off certain sacs of the rumen and in this way allow the effective mixing and stirring of ruminal contents. Mixing of the reticulorumen contents is essential for the fermentative function of the rumen. The entrance to the omasum is off of the reticulum. When reticulorumen contractions occur, they move ingesta into the omasum. The omasum is a muscular organ, the inner surface of which contains many parallel, longitudinal muscular folds. The primary mechanical function of the omasum is to break down food particles further and to convey ingesta into the abomasum. In addition, the omasum absorbs any VFAs not previously absorbed, removes bicarbonate ions from the ingesta (bicarbonate ions would alter the acid pH of the abomasum if removed before passing on), and absorbs some water from the ingesta. The abomasum is the "true stomach" of the ruminant. It functions in much the same way as the monogastric stomach. The small intestine is where the majority of nutrients are absorbed into the bloodstream. It is divided into three segments: duodenum, jejunum, and ileum. um [with an i] that is part of the bony pelvis.)The boundaries between the three segments are not apparent grossly, but microscopic structural differences set them apart from each other. The ﬁrst short segment that leaves the stomach is the duodenum. The jejunum is the longest portion. It makes up the majority of the small intestine. The short ileum enters the colon (large intestine) and is separated from the colon by the ileocecal sphincter (-cecal relates to the term cecum, which is the blind pouch of the large intestine). This sphincter is an anatomical and functional muscle that regulates movement of materials from the small intestine into the colon or the cecum. Although the general functions of the large intestine (cecum, colon, and rectum) are to recover ﬂuid and electrolytes and to store feces until they can be eliminated, the large intestine is another organ of the GI tract that can vary greatly among species. In the carnivores the colon is a rather simple, tubular organ that uses segmental contractions and peristaltic contractions to control movement of feces through it. The cecum, or blind sac, located at the ileocecal junction, is poorly developed in the carnivore but is slightly more developed and larger in the ruminant. Some microbial action on digested foodstuffs occurs in the colon in almost all species. Parasympathetic nervous system stimulation generally causes increased motility in the colon and increased mucus secretion in most species. The exception to the preceding description of the colon is found in nonruminant herbivores best represented by the horse. The "hindgut" (the colon and cecum) in the equine species is very large and acts as its "fermentation vat." The process of expelling feces is called defecation. Many animals voluntarily decide when to defecate for purposes of living with humans, for marking territory, or for preventing detection by scent. The rectum is the terminal portion of the large intestine, and the anus is composed of internal and external muscular sphincters that allow controlled passage of fecal material.

Explain the difference between trade names and generic names of drugs

The generic name is the official accepted name of a drug, as listed in the United States Pharmacopeia ( USP). The designation of USP after a drug name indicates that the drug meets government standards. A drug has only one generic name, but can have many trade names. By law, generic names must be identified on all drug labels. Many companies may manufacture the same drug using different trade ( patented, brand, or proprietary) names. The drug's trade name is prominently displayed and followed by the trademark symbol ™ or the registration symbol ® . For example, ZyPREXA is the trade name and olanzapine is the generic name for the drug shown in Figure 2.1.

List the major glands and hormones that maintain body homeostasis

The hypothalamus is a part of the diencephalon of the brain. It is located in the ventral part of the brain just caudal to the optic chiasma, where the optic nerves cross. It has many important nervous system functions, including appetite control, body temperature regulation, and control of wake-sleep cycles. It also links the conscious mind with the rest of the body by connecting higher centers in the cerebral cortex with lower brain centers and the endocrine system. This link with the endocrine system is accomplished through the control the hypothalamus has over the activities of the pituitary gland. This makes it a very important bridge between the nervous system and the endocrine system. The pituitary gland (also referred to as the hypophysis) is often called the master endocrine gland because many of its hormones direct the activity of other endocrine glands around the body. Physically the pituitary gland is tiny: about the size of a small pea or bean. It is connected to the hypothalamus above it by a slender stalk and is securely housed in a small pocket in the sphenoid bone of the skull called the pituitary fossa. Although it looks like one structure, the pituitary gland is actually two separate glands with completely different structures, functions, and embryological origins. The rostral (front) portion is called the anterior pituitary, or the adenohypophysis. It develops from glandular tissue in an embryo and looks like normal glandular tissue under the microscope. The caudal (rear) portion is called the posterior pituitary, or the neurohypophysis. It develops from the embryo's nervous system and looks like nervous tissue under the microscope. The functions of the two parts of the pituitary gland are as different as their appearance. The anterior pituitary produces seven known hormones, when stimulated by the hypothalamus and direct feedback from target organs and tissues. The posterior pituitary does not produce any hormones. Rather, it stores and releases two hormones that are produced in the hypothalamus and transported to the posterior pituitary along nerze ﬁbers. The following are the seven known anterior pituitary hormones: 1. Growth hormone is also known as somatotropin and somatotropic hormone. Its name comes from its most obvious effect—the promotion of body growth in young animals, particularly the growth of bone and muscle. It has other important roles in animals of all ages, however. It helps regulate the metabolism of proteins, carbohydrates, and lipids in all of the body's cells. 2. Prolactin is named for its effect in the female. It helps trigger and maintain lactation, the secretion of milk by the mammary glands. Once lactation has begun, prolactin production and release by the anterior pituitary gland continue as long as the teat or nipple continues to be stimulated by nursing or milking. If nursing or milking ceases, the production of prolactin will cease as well. Without stimulation from prolactin, the mammary gland "dries up," milk production stops, and the mammary gland shrinks back to its nonlactating size. In the male, prolactin has no known effect. 3. Thyroid-stimulating hormone is also known as thyrotropic hormone. As its name implies, it stimulates the growth and development of the thyroid gland and causes it to produce its hormones. Increased TSH secretion increases thyroid hormone production and vice versa. TSH secretion is regulated by feedback from its target organ—the thyroid gland. This occurs both through direct effects on the anterior pituitary gland and through changes in TSH-releasing factor produced by the hypothalamus. If thyroid hormone levels rise higher than the body needs, TSH production diminishes. With less stimulation, the thyroid gland decreases its hormone production, causing the thyroid hormone level in the bloodstream to drop. If the level drops too low, TSH production increases, stimulating the thyroid gland to increase its hormone production again. Homeostasis of thyroid hormone production is maintained through this interaction among the hypothalamus, anterior pituitary gland, and thyroid gland. 4. Adrenocorticotropic hormone stimulates the growth and development of the cortex (outer portion) of the adrenal gland and the release of some of its hormones. Its production is generally regulated by feedback from the hormones of the adrenal cortex in much the same manner as TSH production is regulated by feedback from thyroid hormones. In times of sudden stress to an animal, however, ACTH can be released quickly as a result of stimulation of the hypothalamus by other parts of the brain. When stimulated in this way, the hypothalamus sends a burst of ACTH-releasing factor down to the anterior pituitary through the portal system of blood vessels that links them, which causes ACTH to be released quickly. 5. Follicle-stimulating hormone is another hormone that is named for its effect in the female. It stimulates the growth and development of follicles in the ovaries. Each follicle is an "incubator" for a single, large female reproductive cell (the oocyte), which develops and matures as the follicle enlarges. This process is termed oogenesis. FSH also stimulates the lining cells of the follicles to produce and secrete estrogens, which are the female sex hormones. Estrogens are responsible for the physical and behavioral changes that prepare the female for breeding and pregnancy. In the male, FSH has an effect similar to one of its effects in the female. It stimulates spermatogenesis, the development of male reproductive cells, the spermatozoa, in the seminiferous tubules of the testes. 6. Luteinizing hormone is yet another hormone whose name is derived from its effect in the female. LH completes the process of follicle development in the ovary that was started by FSH. As a follicle grows, it produces increasing amounts of estrogens that feed back to the anterior pituitary. They cause the production of FSH to decrease and the production of LH to increase. By the time a follicle is fully mature, LH levels reach a peak. In most animal species, this causes ovulation, or rupture of the mature follicle and subsequent release of the reproductive cell. Once ovulation has occurred, the high LH level stimulates the cells left behind in the empty follicle to multiply and develop into another endocrine structure—the corpus luteum. The corpus luteum produces progestin hormones, principally progesterone, which will be necessary for the maintenance of pregnancy should it occur. In the male, LH stimulates cells in the testes called interstitial cells to develop and produce the male sex hormone testosterone. Therefore LH is sometimes called interstitial cell-stimulating hormone (ICSH) in the male. FSH and LH are sometimes grouped together under the term gonadotropins, because they stimulate the growth and development of the gonads—the ovaries and testes. 7. Melanocyte-stimulating hormone Everything in the animal body exists for a reason, although the reason may just be that something is left over from some long-ago time in the species' history. That seems to be the case with our little toe and a horse's splint bones. Melanocyte-stimulating hormone (MSH) may be another remnant of an earlier time, but we have no conclusive evidence one way or the other.MSH is associated with control of color changes in the pigment cells (melanocytes) of reptiles, ﬁsh, and amphibians—animals that can rapidly change colors and color patterns. Administration of artiﬁcially large amounts of MSH to higher mammals can cause darkening of the skin from melanocyte stimulation, but its effect at normal physiological levels is not known. Unlike the very busy anterior pituitary, the posterior pituitary, also called the neurohypophysis, does not produce any hormones. Instead, it serves as a place for two hormones produced in the hypothalamus to be stored for periodic release into the bloodstream. Antidiuretic hormone and oxytocin are transported along nerve ﬁbers down to the posterior pituitary and stored in nerve endings. Nerve impulses from the hypothalamus tell the nerve endings when to release them into the bloodstream. Antidiuretic Hormone. The name antidiuretic hormone (ADH) tells us what it does. It helps prevent diuresis, which is the loss of large quantities of water in the urine. Put more plainly, it helps the body conserve water in times of short supply by acting on the kidneys. ADH causes the kidneys to reabsorb more water from the urine they are producing back into the bloodstream. This makes the resulting urine more concentrated than it would have been otherwise. It has a deeper color and a stronger odor.ADH is released when the hypothalamus detects a water shortage (dehydration) in the body. Oxytocin. The two targets for the hormone oxytocin are the uterus and the mammary glands. In the uterus, oxytocin causes contraction of the myometrium (the muscle of the uterus) at the time of breeding and at parturition. At the time of breeding, oxytocin induces uterine contractions that aid the transport of spermatozoa up to the oviducts. When parturition (the birth process) begins, oxytocin stimulates strong uterine contractions that aid in the delivery of the fetus and the placenta. During a prolonged or difﬁcult labor, oxytocin in the form of an injectable drug is sometimes given to dams to help strengthen weak uterine contractions. However, the myometrium may be "burned out" by overstimulating it with oxytocin, so good clinical judgment must govern its use.The effect of oxytocin on active (milk-producing) mammary glands is to cause what is called milk letdown, or the movement of milk down to the lower parts of the gland.

Describe the gross anatomy of the kidney and urinary system

The kidneys are bean-shaped in most animals and are covered by a ﬁbrous connective tissue capsule. Look at a kidney bean and you'll have a good idea of the origin of its name. The right kidney in horses appears compressed end-to-end, so it becomes somewhat heart-shaped. Kidneys are reddish-brown. Look at that kidney bean again. The color is about right. With the exception of cattle, the kidneys of domestic animals have a smooth surface. The surface of cattle kidneys is divided into about 12 lobes that give it a lumpy appearance. The indented area on the medial side of the kidney is called the hilus. This is the area where blood and lymph vessels, nerves, and the ureters enter and leave the kidney. If you cut the kidney of most animals in half longitudinally through the hilus, you'll ﬁnd a funnel-shaped area inside the hilus. This area is the renal pelvis. It is a urine collection chamber that forms the beginning of the ureter. The renal pelvis is lined with transitional epithelium, the type of epithelium that is capable of considerable stretching without being damaged. Cattle don't have a distinct collection chamber that can be called a renal pelvis. The outer portion of the kidney is called the renal cortex. It is reddish-brown and has a rough granular appearance. The inner portion around the renal pelvis is the renal medulla. It has a smooth appearance with a dark purple outer area that sends rays up into the cortex and a pale, gray-red inner area that extends down to the renal pelvis. The shape of the cortex and medulla and how they relate to each other vary with the species. In some species, such as cattle and pigs, the medulla has numerous, pyramid-shaped areas (they look like candy corn) with the apex pointing to the renal pelvis (pigs) or directly to the ureter (cattle). This gives the medulla a scalloped appearance. The cortex ﬁlls in around the scallops. Kidneys with this structure are called multi pyramidal or multilobar. In other species, such as dogs, horses, and cats, the medullary pyramids fuse to occupy the entire inner area, and the cortex is pushed to the outside area. These kidneys are called unipyramidal or unilobar. The calyx is a cuplike extension of the renal pelvis into which the medullary pyramids ﬁt. The calyces act as funnels that direct ﬂuids into the renal pelvis. From there the ﬂuid will move into the ureter. In cattle, the calyces empty directly into the ureter. The ureters are tubes composed of three layers: an outer, ﬁbrous layer; a middle, muscular layer made up of smooth muscle; and an inner, epithelial layer lined with transitional epithelium. The transitional epithelium allows the ureters to stretch as urine is passed through them on its way to the urinary bladder. The ureters are a continuation of the renal pelvis, and each ureter leaves its kidney at the hilus. The urinary bladder has two parts: a muscular sac and a neck. The bladder looks and acts a lot like a balloon. The bladder sac size and position vary depending on the amount of urine it contains. The bladder is lined with transitional epithelium that stretches as the bladder becomes ﬁlled with urine. The wall of the urinary bladder contains smooth muscle bundles that run lengthwise, obliquely, and in a circular direction. When these muscles contract, the bladder is squeezed and urine is expelled—like letting the water out of the water balloon. The neck of the bladder extends caudally from the sac into the pelvic canal and joins the urethra. Around the neck of the urinary bladder are circular sphincter muscles composed of skeletal muscle ﬁbers. The contraction and relaxation of these sphincter muscles, which are under voluntary control, open and close the passageway for urine to leave the bladder and enter the urethra. This provides voluntary control over the process of urination. When the urinary bladder is empty, it is round and rests on the pubic bones. Structurally it has a thick wall, is lined with many thick folds of transitional epithelium, and has virtually no lumen. In large animals, the empty bladder is conﬁned to the pelvic cavity, but in carnivores, it extends into the abdominal cavity. As the bladder ﬁlls with urine, it becomes pear-shaped, it extends cranially into the abdominal cavity, the folds smooth out, and the wall becomes thinner. The urethra is a continuation of the neck of the urinary bladder that runs through the pelvic canal. Like the ureters and urinary bladder, it is lined with transitional epithelium that allows it to expand. The female urethra is shorter and straighter than the long, curved male urethra. In the female, the urethra opens on the ﬂoor (ventral portion) of the vestibule of the vulva. In the male, the urethra runs down the center of the penis.

Describe the structure and digestive functions of the salivary glands, pancreas, and liver

The liver is the largest gland in the body. The term hepatic refers to the liver. The liver is divided into several hepatic lobes, which are divided further into microscopic hepatic lobules. In mammals, the liver plays an important role in ﬁltering materials absorbed from the GI tract before they have a chance to reach the systemic circulation. The blood vessel system that transports blood from capillaries in the intestines to hepatic capillaries (actually, hepatic sinusoids, or blood-ﬁlled cavities) is called the hepatic portal system. Lining the hepatic sinusoids are phagocytes ("eating cells") that remove bacteria, toxins, poisons, worn-out red blood cells, and other infectious agents that enter the body through the wall of the GI tract. In addition, nutrients like glucose, amino acids, and some vitamins and minerals absorbed from the GI tract are either stored or metabolized by the body in the liver. Bile is produced by hepatic cells. It contains bile acids (or bile salts), cholesterol, and bilirubin (a pigment broken down from the heme pigment in hemoglobin that is released when worn out red blood cells are destroyed). The bile produced is secreted into small canaliculi ("small canals") that merge to form bile ducts. The bile ducts form the hepatic duct, which (in those species that have one) combines with the cystic duct that leads to the gallbladder. The horse does not have a gallbladder. The gallbladder is a storage compartment for bile. Stimulation of the gallbladder by CCK during digestion causes the gallbladder to contract, thereby forcing bile down the common bile duct into the duodenum. In some species the common bile duct fuses with the pancreatic duct before entering the duodenum. The pancreas is both an exocrine gland (secretes substances to the "outside" of the body through a duct) and an endocrine gland (dumping hormones directly into the blood without going through a duct). The exocrine function was detailed in the small intestine, where pancreatic amylase, proteases (trypsin, etc.), and lipase played a critical role in the normal enzymatic digestive process. In addition to the enzymes, the pancreas also secretes signiﬁcant amounts of bicarbonate into the duodenum, which helps neutralize the acid contents coming from the stomach and maintains a pH in the duodenum at which the pancreatic enzymes can function. Insulin and glucagon are two hormones that help regulate blood glucose levels from food that has been digested and absorbed. The beta cells in the pancreatic islets (also known as the islets of Langerhans) produce insulin. Insulin is released in response to elevated blood glucose levels; its action is to move the glucose from the blood into the tissues of the body, thereby effectively supplying the cells with the nutrition they need to function and lowering the concentration of glucose in the blood. A lack of insulin, or a lack of cellular response to insulin, results in an elevated glucose level in the blood and a condition called diabetes mellitus. Glucagon, produced by the alpha cells in the pancreas, antagonizes insulin in that it mobilizes glucose from the liver via gluconeogenesis and glycogenolysis. The combined effects of insulin and glucagon result in blood glucose being tightly regulated in a speciﬁc concentration range, despite varying demands for glucose by the body and changes in carbohydrate in the diet. The salivary glands produce saliva, which performs a variety of digestive and lubrication functions. (Saliva is also involved in evaporative cooling in dogs. Panting evaporates saliva in the mouth, cooling the blood in the capillaries just below the surface of the oral mucous membranes.) Most domestic animals have three matching pairs of salivary glands: (1) the parotid salivary glands, located just ventral to the ear canals; (2) the mandibular salivary glands, located ventral to the parotid glands at the caudal angle of the mandible; and (3) the sublingual salivary glands, located medial to the shafts of the mandible just under the base of the tongue. All of the glands have ducts that carry the saliva to the oral cavity.

Compare and contrast cardiovascular and gastrointestinal drugs

There is a wide variety of different types of drugs to treat cardiovascular and gastrointestinal diseases, but one thing many of them have in common is that they are controlling muscles - either by relaxing them so they constrict less often or by causing them to flex more often or in a controlled manner. GI drugs are many times trying to control diarrhea or vomiting, so are causing the GI muscles to relax and stop the action. Cardiovascular drugs are trying to cause a more regular heartbeat, usually by regulating the beating of the heart - faster or slower. There are many drugs from both sides that don't have anything to do with the muscles, such as laxatives, anti-ulcer and vasodilators.

Summarize the difference between ophthalmic and otic drugs

Topical administration of eye drops or ointment is the most common method of treatment involving disorders of the eye. It is the veterinary technician's duty to educate the client by demonstrating the proper way to administer eye medication. Products for ocular treatment are usually available as solutions or ointments. Drug penetration is one factor that veterinarians must consider when choosing a topical ophthalmic agent. Topical agents are more readily absorbed into the anterior chamber than the posterior chamber. For this reason, these agents have limited use in posterior eye disorders. Systemic agents may be more effective. Lipid-soluble agents readily penetrate the corneal epithelium and endothelium layers. Water-soluble agents readily penetrate the corneal stroma layer. Most topical ophthalmic medications require several applications per day because the eye continuously secretes tears that wash away the medication. Ointments tend to necessitate less frequent applications than do drops. However, ointments may blur an animal's vision for a short period after application. Client education is invaluable during treatment of an eye disorder. When a client obtains a new puppy, the veterinary technician should educate the client regarding the proper way to clean the pup's ears. Performance of the ear cleaning process at an early age will allow the puppy to submit more readily to the task as an adult dog. Unfortunately, those breeds with pendulous ears may tend to have otic problems. Long ear ﬂaps (i.e., pinnae) tend to keep air from circulating into the ear canal; consequently, the ear canal remains moist, creating a perfect environment for yeast formation. Yeast is not the only problem that veterinarians encounter in dogs and cats. External parasites such as Otodectes cynotis and Otodectes procyonis (i.e., ear mites) can cause extreme discomfort in animals that are parasitized by these creatures. Patients whose ears remain untreated often experience aural hematoma caused by extreme shaking of the head. Generally, ear problems are treated with topical medications. Sometimes, ear infections must be treated with systemic medications as well. Topical preparations used to treat ear infections are often a combination of different types of drugs, such as antibacterial, antifungal, antipruritic, and antiinﬂammatory agents. Still other preparations are cleansers, drying agents, and parasiticides. When a ruptured eardrum is suspected or conﬁrmed, oil-based or irritating external ear preparations (e.g., chlorhexidine) and aminoglycosides should be avoided.

Describe the structure and functions of each of the components of the reproductive system

Unlike other body systems, the reproductive system requires a second animal (of the opposite sex) to fully carry out its function, which is to produce a brand new animal (the offspring). What we refer to as the reproductive system in an individual animal is really only half a system. A complete reproductive system is made up of all the male reproductive organs and structures in one animal and all the female reproductive organs and structures in another. Both are necessary for an offspring to be produced The testes have two main functions: spermatogenesis and hormone production. Spermatogenesis is the process by which spermatozoa, the male reproductive cell, are produced in the seminiferous tubules of the testes. Between the seminiferous tubules, cells called interstitial cells (interstitial means between) produce male sex hormones, or androgens. The principal androgen they produce is testosterone, which is responsible for the development of male secondary sex characteristics (such as the male body shape) and the male libido (sex drive). It also has a general anabolic (protein-building) effect on the body, which results in the enhanced muscle and bone development that gives male animals their size and bulk. The scrotum is the sac of skin that houses the testes. Besides providing a home for the testes, the scrotum also helps regulate their temperature. The spermatic cords link the testes with the rest of the body. They are tubelike, connective tissue structures that contain blood vessels, nerves, lymphatic vessels, and the vas deferens. Two layers of connective tissue called the vaginal tunics surround the testes in the scrotum and the spermatic cord. The job of the vas deferens is to propel spermatozoa and the ﬂuid they are suspended in quickly from the epididymis to the urethra when ejaculation occurs. Once they are in the urethra, the spermatozoa are mixed with secretions from accessory reproductive glands to form semen, which is pumped out into the female reproductive tract. The urethra of the male has two functions. Most of the time it carries urine from the urinary bladder outside the body. This is its urinary function. However, when ejaculation occurs, urine ﬂow is temporarily blocked. Spermatozoa from the vas deferens and secretions from the accessory reproductive glands enter the urethra and are pumped out as semen. Ejaculation is its reproductive function. Ducts from the two seminal vesicles, sometimes called vesicular glands, enter the pelvic urethra in the same area as the vas deferens. They are present in all common domestic animals except for cats and dogs. The prostate gland is a single structure that more or less completely surrounds the urethra. Multiple ducts carry its secretions into the urethra. It is present in all common domestic animals. In dogs, it is particularly large because it is the only accessory reproductive gland they have. The penis is the male breeding organ. It is made up mainly of muscle, erectile tissue, and connective tissue, with the urethra running down its center. It has a very large blood supply and many sensory nerve endings. When the male is sufﬁciently aroused and stimulated, the erectile tissue becomes engorged with blood, causing the penis to enlarge and stiffen. This allows it to be inserted into the vagina of the female for breeding The ovaries are the female gonads; they are the female equivalent of the male testes. They are located in the dorsal part of the abdominal cavity near the kidneys. Their shape varies among species; in most, they are somewhat almond shaped, but the ovaries of the horse are indented, making them beanlike in appearance. The ovaries of sows, because their large litter sizes require large numbers of follicles, often look like clusters of grapes. Like the testes, the ovaries have two main functions: producing reproductive cells and hormones. Oogenesis is the process by which ova (the female reproductive cells) are produced in follicles in the ovaries. Unlike spermatozoa, ova are not constantly produced during the reproductive life of the animal. At or soon after birth, the ovaries are seeded with tens of thousands of immature reproductive cells called oocytes. Some of these oocytes will mature into ova, the mature female reproductive cells, through the activities of the ovarian cycle. The rest will either degenerate or never begin development. No more oocytes are produced during the animal's life, however. The number of oocytes in the ovaries soon after birth is the maximum number that will be available to that animal during her lifetime. The two oviducts also are known as the fallopian tubes and uterine tubes; they are small, convoluted tubes that extend from the tips of the uterine horns. Their roles are to guide ova from the ovary to the uterus and to serve as the usual site for fertilization of ova by spermatozoa. The uterus is the womb, where the fertilized ovum implants and lives while it grows and develops into a new animal. When the fetus is fully developed, the uterus helps push it out through the birth canal into the outside world. Although it seems like a simple receptacle in which the fetus can develop, the roles of the uterus are actually quite complex. It has to grow along with the developing offspring and then return to its original size after birth. It forms part of the placenta, which is the life-support system that keeps the fetus alive while it develops during pregnancy. The uterus must remain quiet during pregnancy, and it must contract powerfully at the time of birth. After it has delivered the newborn and the placenta (the afterbirth), it has to contract quickly to stop bleeding from the sites where the placenta was attached to its lining. It does not have the complex, cyclical functions of the ovaries or the intricate structure of the oviducts, but the uterus is vital to the success of reproduction. Physically, the uterus is a hollow, muscular organ. In common domestic animals, it is somewhat Y-shaped, with the uterine body forming the base of the Y and the two uterine horns forming the arms. The cervix is a muscular "valve" that seals off the uterus from the outside most of the time. It is a powerful, smooth muscle sphincter located between the body of the uterus and the vagina. It functions to control access to the lumen of the uterus from the vagina. The cervix is normally tightly closed, except at the two ends of pregnancy: estrus (the heat period) and parturition (the birth process). The cervix opens at estrus to admit spermatozoa during breeding. It then tightly closes again during pregnancy and does not open again until birthing time. Uterine contractions during the ﬁrst stage of labor push the newborn against the cervix and gradually pry it open (called dilation of the cervix) so that "junior" can slide down the birth canal and out into the world. The vagina is the tube that receives the penis at breeding time and acts as the birth canal at birthing time. It is a muscular tube that extends caudally from the cervix and connects it with the vulva. Although the lumen of the vagina is closed most of the time, it can stretch considerably to accommodate the penis at breeding and the newborn during the birth process. Mucous glands lining the vagina lubricate it at the time of breeding. The vulva is the only portion of the female reproductive system that is visible from the outside. Its main parts are the vestibule, the clitoris, and the labia. The word vestibule, in anatomical terms, means the entrance into a canal of some sort. In this case, the vestibule of the vulva is the entrance into the vagina from the outside world. It is the short space between the labia and the opening of the vagina. The urethra, the tube that carries urine out from the urinary bladder, opens on the ﬂoor (ventral portion) of the vestibule. The clitoris is also located on the ﬂoor of the vestibule a little farther to the exterior than the urethral opening. The clitoris is the female equivalent of the penis of the male. It is homologous (equivalent in embryological origin) to the penis and has a similar basic structure. It is attached by two roots and has a body composed of erectile tissue and a glans that is extensively supplied with sensory nerve endings. The labia (lips) form the external boundary of the vulva.

Discuss the functions of related sensory organs

Visceral sensations make up a somewhat miscellaneous category of interior body sensations. Most are vague and poorly localized. They include the sensations of hunger and thirst, which indicate deﬁciencies of nutrients and water. The result of such sensations is the initiation of behaviors designed to secure the needed substances and restore nutrient and ﬂuid balance (homeostasis) in the body. We include touch and pressure together, even though they are sometimes classiﬁed as separate senses. Touch, also known as the tactile sense, is the sensation of something being in contact with the surface of the body. It can be difﬁcult to differentiate touch from pressure, which is the sense of something pressing on the body surface. Different kinds of speciﬁc touch and pressure receptors produce sensations of light contact, deep pressure, vibration, or hair movement. The overall effect is to give the CNS a picture of what, where, and to what extent objects from the outside environment are physically in contact with the surface of the body. The touch and pressure sensations operate almost at an unconscious level, unless the contact is abrupt or the pressure severe. Once physical contact or pressure is initially sensed, it quickly fades into the sensory background unless it changes or is extreme The temperature sense is the monitoring half of the body's temperature control (temperature homeostasis) system. Temperature receptors detect increases or decreases in body temperature and transmit the information to the CNS. The CNS can activate mechanisms to correct conditions of hypothermia (too low a body temperature) or hyperthermia (too high a body temperature) Pain receptors, also called nociceptors, are the most common and widely distributed sensory receptors inside and on the surface of the body. They are found almost everywhere. They range from simple, free nerve endings that respond to intense stimuli of all types, to more specialized structures that detect mechanical forces, temperature, and so on. Their purpose is to protect the body from damage by alerting the CNS to potentially harmful stimuli. Interestingly, the only place in the body where pain receptors are not found is the brain. It is not uncommon for certain types of human brain surgery to be performed on wide-awake patients who have had local anesthesia to allow the brain to be exposed. Without looking at them, can you tell what positions your arms and legs are in? Of course you can, although precisely how you do it may not be clear. You just seem to know where all your body parts are. Actually, you are making use of your sense of proprioception, which is the sense of body position and movement. This sense operates largely at the subconscious level and is very important in allowing an animal to stand upright and make accurate, purposeful movements as it interacts with its environment. During the examination of an animal with suspected nervous system damage, a veterinarian often evaluates proprioception by curling the animal's foot so that it is upside down and seeing how long it takes the animal to right it. Animals with normal proprioception almost immediately bring the foot up into a normal standing position. The sense of taste, also called the gustatory sense, is a chemical sense. Its receptors are located in the mouth in structures called taste buds. When they detect chemical substances dissolved in the saliva, the taste receptors generate nerve impulses that travel to the brain and are interpreted as tastes.The majority of the taste buds are located on the sides of certain small, elevated structures on the tongue called papillae, although a few can be found in the lining of the mouth and throat (pharynx). The sense of smell is also called the olfactory sense. It is a chemical sense very similar to taste. The sense of smell is more important in most nonhuman animals than it is in humans. The sense of smell is organized in two patches of olfactory epithelium located up high in both nasal passages. Figure 14-3 shows the location and some of the structure of the olfactory epithelium. Sensory (olfactory) cells are mixed with supporting cells in these epithelial patches. Hairlike processes (modiﬁed dendrites) from the surfaces of the olfactory cells project up into the mucous layer that covers the nasal epithelium. When odor molecules dissolve in the mucus and contact the sensory processes, nerve impulses are generated that travel to the brain and are interpreted as particular smells. Hearing, also called the auditory sense, is a mechanical sense that converts vibrations of air molecules into nerve impulses that are interpreted by the brain as sound. The ear, the organ of hearing, can be divided into three physical and functional areas: the external ear, the middle ear, and the inner ear. The external ear acts as a funnel to collect sound wave vibrations and direct them to the eardrum. The middle ear ampliﬁes and transmits the vibrations from the eardrum to the inner ear. The inner ear contains the actual sensory receptors that convert the mechanical vibrations to nerve impulses, along with receptors for the equilibrium sense. As the head goes, so goes the rest of the body. At least that is the principle behind the sense of equilibrium. This mechanical sense helps the animal maintain balance by keeping track of the position and movements of the head. Its receptors are located in portions of the inner ear called the vestibule and the semicircular canals.Actually, maintaining balance is a complicated process that involves information from the equilibrium receptors, as well as from the eyes and the proprioceptors around the body. The eyes have a lot in common with electronic cameras. They have lens covers (the eyelids), a "window" to let light in (the cornea), an adjustable diaphragm to control the amount of light that enters (the iris), a lens that can be focused, light detectors on which the image is formed (rods and cones in the retina), and a cable to carry the images to a recorder (the optic nerve).As complicated as the eye seems, most of its components exist to help form an accurate visual image, not to detect one. The actual photoreceptors that detect the image and generate visual nerve impulses are in a single layer of cells in the retina (the structure that lines the back of the eyeball). In our discussion of vision, we'll deal mostly with the image-formation structures of the eye.

Explain the principles of large-animal and exotic radiographs

Working with large animal patients requires much patience and time. Any procedure performed must be well thought out before it is started. The radiographer must also expect the unexpected. Successful large animal radiography is the result of forming a plan before the examination, teamwork during the examination, and patience throughout. Although the differences between large and small animals are great, the principles of radiography are essentially the same. All directional terms and positions that apply to a dog and a cat apply to a horse and a cow. The two major differences are size and posture. In large animal radiography, unless the animal is young or small enough to be placed on an x-ray table, the patient is in a standing position. The size and posture of the patient necessitate special consideration in the areas of patient restraint, equipment, patient preparation, radiation safety, and positioning devices. In a standing position, the large animal patient is relatively unrestrained. Because of this, there is a greater risk of injury to personnel and to the x-ray machine. The x-ray tube is particularly vulnerable because it must be positioned close to the animal's leg and is liable to be kicked. The radiographic machinery required for large animals must have adequate power and easy maneuverability. The x-ray tube must be able to move horizontally around the standing patient and vertically to expose an area as low as the level of the floor. The x-ray machines used for radiography of large animals fall into three categories: (1) small portable units, (2) mobile units, and (3) mounted units. Careful preparation of the patient is necessary for an artifact-free radiograph. For all examinations, the hair coat should be brushed or washed to remove obvious dirt, bedding, and other surface artifacts. The areas of interest also should be wiped dry with a towel to remove any water or other remaining liquid contaminants. For radiography of the equine foot, a number of steps are necessary to prevent extraneous radiographic shadows over the areas under examination. The ﬁrst step is to remove the shoe of the patient and trim back any overgrown portions of the hoof. Next, the sole and clefts should be picked and scrubbed clean. The ﬁnal step is to pack the sole of the foot with a radiolucent material such as methylcellulose, softened soap, or Play-Doh. Packing the sole prevents the appearance of an air artifact superimposed over the areas of interest. The attendants holding the patient and holding the cassette next to the anatomy must be wearing appropriate lead attire. Because the attendants' attention is focused on the patient rather than the x-ray beam, it is the responsibility of the radiographer to ensure that all personnel are a safe distance from the primary beam. Cassette-holding devices help reduce exposure to the attendants. The device usually consists of a clamp that is attached to the cassette and held at length by a handle. At times, it may be necessary to raise the animal's foot because the x-ray tube cannot be dropped to the level of the floor. A positioning block can be used to raise the foot into position and to serve as a cassette holder. The block is usually constructed of wood built to suit the particular x-ray unit. A slot can be cut into the wood to serve as a cassette holder. The foot of the patient can be placed directly onto the block to raise it into position next to the cassette, or the cassette can be placed beside the block. Another device that is often necessary is a cassette tunnel. A tunnel can be constructed of a radiolucent wood or hard plastic, but it must be durable enough to withstand the weight of the patient. For a dorsopalmar/dorsoplantar oblique view of the cofﬁn or navicular bone, the patient must be standing on top of the cassette. A cassette cannot withstand such weight without sustaining damage. A tunnel device can make the examination possible without damaging the equipment. Birds and exotic pets including rodents, reptiles, and ﬁsh have become popular in recent years. Consequently,veterinary practitioners have experienced increased demand for diagnostic and therapeutic care of these animals. Radiography is a valuable diagnostic technique because it is noninvasive and available for rapid interpretation. All principles pertaining to companion animal radiography can be applied to avian and exotic radiography. Avian and exotic patients usually are not measured with a caliper to calculate the exposure. Normally,exposure factors are chosen according to the species and general size of the patient. Keep in mind that the exposure factors required for birds are less than those necessary for reptiles of the same thickness. Soaring (flying) birds have thin cortices and tubular bones. Compared with mammals, avian long bones have signiﬁcantly less calcium and ossiﬁcation, which makes them more radiolucent. Slight exposure variations can produce marked alterations in radiographic images of birds. Three types of restraint are used for avian and exotic patients during radiography: (1) manual, (2) physical, and (3) chemical. Regardless of the species and restraint device used, the methods of restraint are similar. The head and torso are restrained ﬁrst, then the wings (in the case of a bird), and the legs last. With larger rodent mammals, it is possible to use the same restraint methods as for a dog or cat.

Describe how a radiographic image is produced

X-rays are generated in an x-ray tube. The tube consists of a cathode side (with a negative electrical charge) and an anode side (with a positive charge). In the tube, a stream of fast-moving electrons is attracted and directed from the cathode to the anode. As the electrons collide and interact with the atoms on the anode target, a great amount of energy is produced; 1% of this energy is in the form of x-radiation. The cathode consists of a wire ﬁlament that emits electrons when heated. The ﬁlament temperature is controlled by the mA setting on the console of the machine. As the mA is increased, the temperature of the ﬁlament is increased and the ﬁlament produces more electrons. The period of time during which the electrons (x-rays) are permitted to leave the x-ray tube is measured in fractions of seconds. The number of electrons available and the time period set for their release determine how many x-rays are available. The mAs thus control the total number of x-rays produced. The anode, which attracts negatively charged electrons, is angled so that the x-rays produced are directed downward (toward the ﬁlm) through a window in the metal housing of the x-ray tube. The electron speed necessary to create a high-energy impact is achieved by applying thousands of volts (kVp) across the anode and cathode ﬁeld. High voltage produces x-rays with greater penetrating power and intensity. The kVp thus controls the penetrating power of the x-rays. Imagine yourself in a grocery store, with a grocery cart and ready to go. Your purpose, however, is not to shop for the week's food but to knock down a large pile of tomato juice cans stacked in a pyramid. The pyramid is located in the center of the store and stands 10 feet tall. To accomplish your goal, you have only the cart and all the muscle you can muster. With a running start, you head for the pyramid. Despite your running speed and strength, you are unable to knock down all of the cans of tomato juice—only a few are displaced. The grocery cart is stopped in its tracks, and you are thrown into the produce aisle. Among the canned goods, you decide to put something inside the cart to increase its weight. Perhaps the momentum of a heavy cart pushed with great force will knock down the pyramid. You ﬁll the cart with cans of beans. Straining with effort, you slowly push the cart toward the stack of juice cans. Because of the extreme weight in the cart, your strength is insufﬁcient to break through the pyramid. Feeling a bit dismayed, you sit once again. But with sudden inspiration, you remove half the beans from the cart and again race toward the stack of juice cans. The sufﬁcient weight and your adequate strength enable you to topple the entire pyramid. To apply this parable, it is necessary to examine the facts. To topple the pyramid, you needed a certain number of cans of beans in the cart and sufﬁcient strength to push the cart. The beans represent the amount of electrons (number of x-rays) or mAs, the muscle power pushing the cart represents the kVp, and the pyramid represents the patient. If there are insufﬁcient mAs (beans), it is impossible to produce a good-quality radiograph, regardless of the amount of kVp (pushing power). Similarly, regardless of the amount of weight in the cart, it is impossible to penetrate the pyramid if there is inadequate strength (kVp). The necessary amount of muscle and beans always depends on the size of the pyramid. The amount of mAs and kVp required for a given patient depends on the density of the anatomic part being radiographed.

Explain the veterinary technician's role in inventory control

depending on the policies at the clinic the vet tech works at, he/she may be required to do regular inventory and place orders to re-stock the pharmacy shelves with medications as well as vaccines. The entire process will depend on the policies of the clinic, but ordering may happen on a regular basis so items can be ordered in smaller quantities, or orders may only come in once a month - or less frequently. Ordering of items will depend on how much stock should be kept on hand as well as how quickly things are used. If a tech has the ability to take on this responsibility, they become more valuable to their clinic.

List the units of measure used in the metric system

kilo - k - 1,000 hector - h - 100 deka - da - 10 BASE UNIT - g, L, m- 1 deci - d - 0.1 centi - cm - 0.01 milli - m - 0.001 micro - mc - 0.0000001

Define common terms used in general pharmacology

see list of terms

Describe the dangers of x-rays

All living cells are susceptible to ionizing radiation damage. Affected cells may be damaged or killed. Cells that are most sensitive to radiation are rapidly dividing cells (e.g., growth cells, gonadal cells, neoplastic cells, and metabolically active cells). Therefore persons younger than 18 years of age and pregnant women should not be involved in radiographic procedures. Other tissues that are readily sensitive to radiation include bone, lymphatic, dermis, leukopoietic and hemopoietic (blood forming), and epithelial tissues. Somatic damage describes damage to the body that becomes manifest within the lifetime of the recipient. Radiation can produce immediate changes in the cell, although the damage may not be apparent for some time. Because the body has the ability to repair itself, cell damage may never be appreciated or visible. Damage is more extensive when the body is exposed to a single massive dose of radiation than to smaller, cumulatively equivalent repeated exposures. As mentioned earlier, body cells are not equally sensitive to radiation, and the healing process varies among cell types. Examples of somatic damage include cancer, cataracts, aplastic anemia, and sterility. Genetic damage from radiation occurs as a result of injury to the genes (DNA) of reproductive cells. Ionizing radiation can damage chromosomal material within any cell. The result of the damage is determined by the cell type (i.e., somatic cell or reproductive cell). Damage to reproductive cells can result in the effect known as gene mutation. Genetic damage is not detectable until future generations are produced. The offspring of irradiated persons may be abnormally formed because of changes in the hereditary material, resulting in alteration of the individual phenotype (physical appearance).The mutation may be lethal or may be only a visible anomaly. The gene mutation may also stay latent or recessive until the second or third generation. Mortality from radiation is caused by exposure to extremely high levels of radiation. Exposure to a large, single dose of radiation, as from a hydrogen bomb, is necessary to cause rapid death. A single exposure to a dose of 300 rad (radiation absorbed dose; see later) or more has been shown to be lethal to humans. Further information on death due to radiation exposure can be found in a radiobiology textbook. A technologist working in a practical situation and following proper safety protocol should never receive this level of radiation. Because the body has the ability to repair itself, accumulative smaller doses of radiation are sublethal. Theoretically, no amount of radiation is nondamaging. Even under the best conditions, some exposure to ionizing radiation will occur. Therefore it is the responsibility of radiographers to limit the exposure of ionizing radiation to patients, clients, and themselves. The exposure received by any individual should never exceed the maximum permissible dose.

Use dimensional analysis to calculate dosages

Dimensional analysis sounds very technical but it is actually a very simple and logical method of converting units of measurement from one form to another. In the medical sciences, we often meet problems where we are dealing with different systems of measurement, and this method allows us to change the measurement type to ﬁt the situation. How do we arrive at the answer unit from the starting factor? We use one or a series of conversion factors. Conversion factors are ratios of units of measurement that have a true relationship and are expressed as fractions with a numerator and denominator. Setting up an equation using dimensional analysis can be broken down into these seven steps: 1. Identify the starting factor 2. Identify the answer units 3. Determine the conversion factors needed 4. Ensure the conversion factors are in the correct format to give you the desired answer unit 5. Cancel units that appear in both the numerator and denominator 6. Simplify the fractions 7. Complete the equation.

Describe the six "rights" of medication administration

In order to prepare and administer drugs safely, it is imperative that you understand and follow the Six Rights of Medication Administration: Right drug - it should be the drug that best fits the patient's symptoms with the least side-effects / drug interactions Right dose - the right dose for the size and age of the animal and the symptoms Right route - should it be pill, injection, topical, inhalation Right time - the correct number of times per day Right patient - labels should be double checked to be sure the drugs are for the right patient Right documentation - the patient's chart should include the prescription of the drug as well as the correct dosage to ensure the dispensed drug and future refills. These six "rights" should be checked before administering any medications. Failure to achieve any of these rights constitutes a medication error. Patients need to be educated about their medications, and if a patient refuses a medication, the reason must be documented and reported.

Explain the function of the endocrine system

Put most simply, the endocrine and nervous systems help maintain homeostasis (balance) in the body. These two systems constantly send instructions to the rest of the body, telling it how to respond to changing internal and external conditions. Both systems use chemicals to transmit their messages, but they do it by different means. The endocrine system messengers, hormones, are produced by endocrine gland cells, or modiﬁed neurons. They travel through the bloodstream to distant cells and tissues, where they produce their effects. The nervous system messengers, called neurotransmitters, are produced only by neurons. They travel very short distances across synaptic spaces to produce their effects. The targets of hormones are all of the cells and tissues in the body. The targets of neurotransmitters are generally only muscle cells, glands, and other neurons. The endocrine system reacts slowly to changes but can sustain its responses for long periods. The nervous system reacts more quickly to changes but cannot sustain prolonged responses. The basic units of the endocrine system are endocrine glands. Located throughout the body, endocrine glands secrete tiny amounts of hormones directly into the bloodstream. This method of secretion gives them the nickname ductless glands. This feature differentiates them from exocrine glands (exo means "out" or "external"), which secrete their products onto epithelial surfaces through tiny tubes called ducts. The hormones produced by the endocrine glands circulate throughout the body and produce effects whenever they ﬁnd friendly receptors they can attach to, either in or on the cells.

Recognize acceptable safety procedures

Radiation Safety Rules: A Checklist • Remove all unnecessary personnel from the radiographic suite during exposure. • Never permit persons younger than age 18 or pregnant women in the radiographic suite while it is in use. • Rotate personnel who assist in radiographic procedures to minimize exposure. • Use mechanical restraints whenever possible (e.g., sandbags). • Use chemical restraint whenever possible (anesthetize or tranquilize). • Always wear protective apparel designed to absorb secondary radiation effectively (0.5-mm lead thickness). • Ensure maximum life of protective apparel through proper use and care. • Never permit any part of the body to be within the primary beam whether shielded or not. • Use collimation whenever possible to decrease ﬁeld size and scatter radiation. • Use a 2.5-mm aluminum ﬁlter to remove soft x-rays from the primary beam. • Do not aim the x-ray beam directly at any personnel or adjacent occupied room. • Never handhold the x-ray tube. • Wear ﬁlm or TLD badges near the collar, outside the lead apron, to monitor radiation exposure to the thyroid gland, face, and eyes. • Plan the radiographic procedure carefully to avoid unnecessary retakes. • Maintain darkroom chemicals in good operating condition. • Have the x-ray machine calibrated annually by a qualiﬁed service representative. • Keep an exposure log that identiﬁes the patient, the type of study performed, and the exposure values. • Adhere to the radiation safety codes for your state. • Remember that patience is an important virtue.

Explain how the nervous system receives and interprets stimuli as well as controls body actions

Some nerves conduct electrical impulses from the periphery toward the CNS, and other nerves conduct impulses in the opposite direction, from the CNS toward the periphery. These two functional types of nerves are called afferent nerves and efferent nerves. Afferent nerves conduct nerve impulses toward the CNS (ad means "toward," and ferre means "to carry"), whereas efferent nerves conduct nerve impulses away from the CNS (ex, "away"; ferre, "to carry"). Because afferent nerves conduct sensations from the sensory receptors in the skin and other locations in the body to the CNS, afferent nerves are also called sensory nerves. In contrast, efferent nerves conduct impulses from the CNS out toward muscles and other organs. Because the efferent impulses are the ones that, among other things, cause skeletal muscle contraction and movement, efferent nerves are often called motor nerves. Cranial and spinal nerves in the PNS and nerve tracts (bundles of axons) in the CNS may carry nerve ﬁbers that are sensory, motor, or a combination of both. When an animal turns its head in response to its name being called by its owner, efferent (outgoing) motor impulses from the brain are consciously sent to the muscles in the neck to turn the head toward the sound. This conscious, or voluntary, control of skeletal muscles is referred to as a somatic nervous system function. Because the action of the animal turning its head was caused by voluntary initiation of efferent impulses, this function would be classiﬁed as a somatic motor function. Impulses being sent to the CNS from receptors in the muscles, skin, eyes, or ears would be classiﬁed as somatic sensory functions, because they are consciously perceived by the brain. Resting state. Sodium has been pumped out of the cell and potassium has been pumped in, producing a net negative electrical charge inside the cell membrane compared to the outside. Depolarization. A stimulus has caused the gate on the sodium channel to open, allowing sodium ions to ﬂow into the cell. This produces a net negative charge on the outside of the cell membrane—the opposite of the resting state. Beginning of repolarization. The gate on the sodium channel is closing and the gate on the potassium channel is opening to allow potassium ions to ﬂow out of the cell. Repolarization. A sufﬁcient outﬂow of potassium ions has restored the net negative charge to the inside of the cell, but the sodium and potassium ions are on opposite sides of the cell membrane from where they started. The restoring resting state is when Sodium ions are pumped out of the cell and potassium ions are pumped into the cell.

Distinguish between hormonal, endocrine, and reproductive drugs

The traditional deﬁnition of the endocrine system states that it is composed of organs (glands) or groups of cells that secrete regulatory substances (hormones) directly into the bloodstream. This deﬁnition has now been extended to include regulatory substances that are distributed by diffusion across cell membranes. The endocrine system and the nervous system constitute the two major control mechanisms of the body. These two control mechanisms are linked together through the complex integrating action of the hypothalamus. Coordination of these two systems allows an individual to adapt its reproductive and survival strategies to changes in the environment. Endocrine glands include the pituitary, adrenals, thyroid, ovaries, testicles, pancreas, and kidneys. These glands produce hormones that are carried to target organs, where they inﬂuence the physiologic activity of these structures. Hormones generally are administered to animals for one of two reasons: (1) to correct a deﬁciency of that hormone, or (2) to obtain a desired effect (e.g., to postpone estrus). Hormones that are administered to an animal are called exogenous hormones, whereas those produced naturally in the body are endogenous hormones. HORMONAL DRUGS ASSOCIATED WITH REPRODUCTION Gonadotropins and Gonadal Hormones Products in this category are used in veterinary medicine for various reasons. Some of these include synchronization of estrus, suppression of estrus, induction of estrus, treatment of cystic ovaries, and termination of pregnancy. Gonadotropins are drugs that act similarly to GnRH, LH, or FSH. Gonadotropins cause the release of LH and FSH or cause activity like that of LH or FSH. LH may be prepared from the pituitary glands of slaughtered animals or obtained from the urine of pregnant women in the form of human chorionic gonadotropin (hCG). FSH may be obtained from pituitary glands (FSH-P) and from the serum of pregnant mares (PMS) between the 40th and 140th days of pregnancy. GnRH is prepared synthetically. FSH that is released endogenously by the anterior pituitary causes growth and maturation of the ovarian follicle in females and spermatogenesis in males. LH, also released by the anterior pituitary, causes ovulation in females and production of testosterone in males. Gonadotropins are drugs that act similarly to GnRH, LH, or FSH. Gonadotropins cause the release of LH and FSH or cause activity like that of LH or FSH. LH may be prepared from the pituitary glands of slaughtered animals or obtained from the urine of pregnant women in the form of human chorionic gonadotropin (hCG). FSH may be obtained from pituitary glands (FSH-P) and from the serum of pregnant mares (PMS) between the 40th and 140th days of pregnancy. GnRH is prepared synthetically. FSH that is released endogenously by the anterior pituitary causes growth and maturation of the ovarian follicle in females and spermatogenesis in males. LH, also released by the anterior pituitary, causes ovulation in females and production of testosterone in males. Estrogens are a group of hormones synthesized by the ovaries and—to a lesser extent—by the testicles, adrenal cortex, and placenta. Estrogens are classiﬁed as sex steroids and are synthesized from a cholesterol precursor. Estrogens are necessary for normal growth and development of the female gonads. They cause secondary female characteristics and are responsible for female sex drive. These hormones inhibit ovulation, increase uterine tone, and cause proliferation of the endometrium. Androgens are male sex hormones produced in the testicles, the ovaries, and the adrenal cortex. Similar to the other gonadal hormones, they have a steroidal parent molecule. These hormones are necessary for growth and development of the male sex organs. They cause secondary male sex characteristics and produce male libido. The androgens promote tissue anabolism, weight gain, and red blood cell formation. Progestins are a group of compounds that are similar in effect to progesterone. Endogenous progestins are produced by the corpus luteum. They cause increased secretions by the endometrium, decreased motility in the uterus, and increased secretory development in the mammary glands. They also inhibit the release of gonadotropins by the pituitary to produce an inactive ovary. In some situations, they can cause elevated blood glucose levels (antiinsulin effect) or serious suppression of the adrenal glands. These hormones are used clinically to suppress estrus and to treat false pregnancy, behavioral disorders, and progestin-responsive dermatitis. The root "gest" often allows name recognition of the progestins. Prostaglandins consist of a group of naturally occurring, long-chain fatty acids that mediate various physiologic events in the body. The primary use of prostaglandins in veterinary medicine is for regulation of activity in and treatment of conditions of the female reproductive tract. Of the six classes (A, B, C, D, E, and F), only prostaglandin F2alpha has signiﬁcant clinical application in the reproductive system. Prostaglandin F2alpha causes lysis of the corpus luteum, contraction of uterine muscle, and relaxation of the cervix. Lysis of the corpus luteum results in a decline in plasma levels of progesterone and, through the negative feedback mechanism, initiation of a new estrus cycle. Contraction of uterine muscle can facilitate evacuation of uterine contents (pus or a mummiﬁed fetus) or produce an abortion. Bronchoconstriction, increased blood pressure, and smooth muscle contraction have been reported in other species, including humans. For these reasons, pregnant women and asthmatic individuals should handle prostaglandin products with extreme caution; exposure (through injection or skin contact) can cause abortion or an asthma attack. Name recognition of the prostaglandins is made easier by looking for "prost" in the drug name. Dinoprost tromethamine is a salt of the naturally occurring prostaglandin F2alpha and is labeled for use in cattle, horses, and swine. It also has accepted clinical uses in dogs, cats, sheep, and goats. It is effective only in animals with a corpus luteum. Fenprostalene is a synthetic analog of prostaglandin F2alpha. Fenprostalene produces effects similar to those of dinoprost and the other class F prostaglandins. It is labeled for synchronization of estrus and as an agent to induce abortion (at 150 days or fewer of gestation) in cattle. Fluprostenol is a synthetic analog of prostaglandin F2alpha for use in mares. Cloprostenol sodium is an analog of prostaglandin F2alpha for use in cattle. This product is chemically very similar to dinoprost and fenprostalene and is labeled for uses in cattle that are very similar to those of dinoprost and fenprostalene. The same precautions should be taken when this drug is used as are taken with the other prostaglandins. Cloprostenol sodium is an analog of prostaglandin F2alpha for use in cattle. This product is chemically very similar to dinoprost and fenprostalene and is labeled for uses in cattle that are very similar to those of dinoprost and fenprostalene. The same precautions should be taken when this drug is used as are taken with the other prostaglandins. Drugs That Affect Uterine Contractility Several drugs have the ability to increase the contractility of uterine muscle. Some are used during pregnancy to cause abortion, and others are used at term to induce parturition, to aid in delivery of the fetus or the placenta, and to cause involution of the uterus after delivery. Great care should be taken to ensure that the cervix is dilated before these drugs are administered. Oxytocin is a polypeptide made in the hypothalamus and stored in the posterior pituitary for release in response to appropriate stimuli from the reproductive tract or mammary glands. This hormone causes stronger uterine contractions by increasing the contractility of uterine myoﬁbrils. The uterus must be primed for a period by progesterone and estrogen before oxytocin is effective in stimulating the uterus. Oxytocin is used clinically to cause more forceful uterine contractions as an aid in delivery of a fetus. It is also used to assist delivery of the placenta, to cause uterine involution, and to reduce bleeding of the uterus after delivery. It should be used only when the cervix is sufﬁciently dilated and when it can be determined that the fetus can be delivered normally through the pelvic canal. This hormone is responsible for milk letdown from the mammary glands through its stimulation of myoepithelial cells in the alveolar wall of the glands. It is released endogenously after stimulation of the udder or in response to environmental stimuli, such as the sound of milking machines or other sights, sounds, or smells associated with nursing/milking. Ergot is a fungus that grows on rye grass and possibly on some pasture grasses. It causes smooth muscle contraction and can cause intense vasoconstriction. If the vasoconstriction is severe enough, gangrene and sloughing may occur. Ergonovine maleate has been used in veterinary medicine because it produces uterine contractions similarly to oxytocin. It results in very little vasoconstrictive action, however. This product is not commonly used. Prostaglandins, as mentioned in a previous section, stimulate uterine smooth muscle and can be used to induce parturition or abortion. Corticosteroids comprise a group of hormones produced by the adrenal cortex that are used primarily for their antiinﬂammatory effect but can cause induction of parturition in the last trimester of pregnancy. This effect occurs because exogenous administration of the drug mimics the natural rise in production of corticosteroids by the fetus as the time for delivery draws near. Induction of parturition or abortion is not a labeled use for the corticosteroids, but they have been applied clinically for this purpose. Miscellaneous Reproductive Drugs Bromocriptine is a dopamine agonist and prolactin inhibitor that has been used mainly in dogs for pregnancy termination after mismating or for the treatment of pseudopregnancy. Leuprolide is a synthetic analog of gonadotropin releasing hormone that is used for the treatment of adrenal endocrinopathy in ferrets and for the treatment of inappropriate egg laying in cockatiels. Melatonin is a naturally occurring hormone that is produced in the pineal gland. In addition to its use in the treatment of alopecia in dogs and sleep disorders in cats and dogs, melatonin has been used to improve early breeding and ovulation in sheep and goats. Neutersol is a U.S. Food and Drug Administration (FDA)-approved product that contains the amino acid l-arginine and a zinc salt; it is administered directly into the testicles of puppies to cause permanent sterility. It reportedly does not eliminate testosterone production and its associated behavioral characteristics, however. Drugs Used to Treat Hypothyroidism Treatment of hypothyroidism consists of supplementation of thyroid hormones on a daily basis. Clinical signs usually resolve within a short time of treatment initiation, but lifelong therapy is required. Thyroid hormones can be extracted from thyroid glands or can be prepared synthetically. Puriﬁcation of the animal source hormones is difﬁcult and has led to the common use of synthetic products. Synthetic thyroxine (T4) is considered to be the compound of choice in the treatment of hypothyroidism. T3 products are recommended only when a poor response to T4 occurs. Levothyroxine Sodium (T4) Levothyroxine is a synthetic levo isomer of T4. It is the compound of choice for the treatment of hypothyroidism in all species. Liothyronine Sodium Liothyronine sodium (T3) is a synthetic salt of endogenous T3. T3 is not the compound of choice for the treatment of hypothyroidism. It may be useful, however, in cases that do not respond well to T4. Thyroid-Stimulating Hormone Thyrotropin is a puriﬁed form of TSH obtained from the anterior pituitary in cattle. It is used as an aid in the diagnosis of hypothyroidism. Treatment of hyperthyroidism is directed at lowering blood levels of T3 and T4. This can be accomplished by destruction or removal of the overproducing thyroid or by blocking of hormone production. The thyroid can be removed surgically or destroyed with radioactive iodine. Drug therapy to block hormone production can be effective but is continuous and is not curative. The two antithyroid drugs used most often are methimazole and carbimazole. These compounds are used for long-term therapy and for presurgical preparation of patients. Hyperthyroid cats are often high surgical risks, primarily because of tachycardia and other potential cardiac abnormalities. Methimazole is a compound that interferes with incorporation of iodine into the precursor molecules of T3 and T4. It does not alter thyroid hormones already released into the bloodstream. Carbimazole is a product similar to methimazole that is used in Canada and other countries. Most of this drug is converted to methimazole after administration to the cat. It inhibits the synthesis of thyroid hormones. Ipodate is an orally administered, radiopaque, organic iodine compound that is thought to inhibit the conversion of T4 to T3. Propylthiouracil has been used as an antithyroid drug but is considered dangerous for use in cats because of potential hematologic complications. Radioactive iodine (I-131) may be given intravenously to destroy overproductive thyroid tissue. I-131 concentrates in the thyroid, where it remains and destroys thyroid tissue. This method has appeal because it is performed only once and is not especially stressful to patients. However, it must be done at facilities that can handle radioactive materials. Propranolol (Inderal) may be used preoperatively to treat the tachycardia associated with hyperthyroidism in cats. Agents for the Treatment of Diabetes Mellitus The pancreas produces two principal hormones in special cells of the islets of Langerhans: insulin and glucagon. Insulin is produced by beta cells, and glucagon is produced by alpha cells. Insulin causes a decrease in blood glucose levels, and glucagon promotes an increase. Only insulin is used clinically. Insulin facilitates cellular uptake of glucose and its storage in the form of glycogen and fat. It inhibits the breakdown of fat, protein, and glycogen into forms that may be used as energy sources. Further, it promotes synthesis of protein, fatty acids, and glycogen. In the absence of insulin, the body cannot use glucose and must break down its own fat and protein that can be used for energy.

Summarize the functions of the peripheral nervous system and the autonomic nervous system

The peripheral nervous system (PNS) is made up of those components of the nervous system that extend away from the central axis outward, toward the periphery of the body. The cranial nerves are those nerves of the PNS that originate directly from the brain, and spinal nerves are those PNS nerves that emerge from the spinal cord. In contrast to the voluntary movement of the somatic nervous system function, animals do not have to consciously think to contract their intestines, increase their heart rate in response to a threat, or stimulate release of digestive juices in response to ingestion of a meal. The animal also does not have to be consciously aware of blood pressure receptors informing the body that the blood pressure is too low or of stretch receptors indicating that the lungs have inﬂated. The part of the nervous system that controls and coordinates these automatic functions is called the autonomic nervous system (auto means "self," and nomos means "law," so the autonomic nervous system is the self-regulating system.) Like the somatic (voluntary) system, the autonomic system also has motor nerves and sensory nerves. However, instead of these motor nerves going to skeletal muscle to cause voluntary limb or body movement, these autonomic motor nerves send impulses to smooth muscle, cardiac muscle, and glands to regulate a wide variety of automatic body functions. Autonomic sensory nerves receive the afferent sensory impulses from sensory receptors that are used to automatically regulate these body functions. The autonomic nervous system controls many functions of the body at a subconscious level. These automatic functions are performed by two divisions of the autonomic nervous system: the sympathetic nervous system and the parasympathetic nervous system. These two systems generally have opposite effects on organs or tissues, and whichever system dominates at any given moment determines the state of the organ systems. The ﬁrst anatomical difference between these two systems is where the peripheral nerves of each system emerge from the CNS. The nerves for the sympathetic nervous system emerge from the thoracic and lumbar vertebral regions in the back. Thus, the sympathetic system is often referred to as the thoracolumbar system. In contrast, the parasympathetic system emerges from the brain and the sacral vertebral regions and therefore is called the cranial-sacral system. The sympathetic nervous system is often called the ﬁght-or-ﬂight system, meaning that this is the system that helps the body cope with emergency situations in which an animal might have to defend itself (ﬁght) or escape (ﬂight). In contrast, the parasympathetic nervous system could be called the rest-and-restore system because of its ability to decrease the strong excitatory effects of the ﬁght-or-ﬂight system (bring the body back to resting state) and its ability to facilitate all the processes that will replace those body stores used up during the emergency (restore).

Discuss the procedure for performing common contrast studies

The two basic categories of contrast media are positive and negative. Positive-contrast agents, such as barium or iodine compounds, contain high atomic number elements. These agents absorb more x-rays than do soft tissues or bones. Positive-contrast media are radiopaque to x-rays and appear white on a radiograph. These compounds can be used to ﬁll or outline a hollow organ (e.g., urinary bladder, alimentary tract), or they can be injected into a blood vessel (sterile, water-based compounds only) for immediate visualization of the vascular supply or for subsequent excretion evaluation. Negative-contrast agents consist of gases (e.g., oxygen, carbon dioxide) that have a low speciﬁc gravity. Substances with a low speciﬁc gravity are more radiolucent to x-rays than are soft tissues and have a black appearance on a radiograph. Many different compounds are used as radiographic contrast media. In addition, various manufacturers market identical contrast agents under different names and concentrations. Although it is virtually impossible to become familiar with all of the contrast agents available, it is possible to place them into one of three general categories: (1) positive-contrast iodinated preparations, (2) positive-contrast barium sulfate preparations, and (3) negative-contrast gases. Each category has basic characteristics used to classify contrast agents. These characteristics allow a better understanding of each individual medium. The majority of agents currently available are intended for human use; however, some products are speciﬁcally approved by the U.S. Food and Drug Administration for animals. Contrast agent choice should be made on the basis of the type of study to be performed, the condition of the patient, the possible side effects, and the judgment of the veterinarian that it is the best available product for use. Proper patient preparation is vital to a diagnostic radiographic study. Before the study, the patient's gastrointestinal tract should be emptied by withholding food for 12 to 24 hours and, if necessary, administering a cleansing enema. The presence of any gastrointestinal contents can detract from a quality study and may obstruct the view of certain areas of interest as a result of superimposition. Keep in mind that cathartics and enemas often produce gastrointestinal gas. To reduce the amount of gas present in the gastrointestinal tract during a study, the cathartic should be administered 4 to 12 hours before the radiographic procedure, and a radiographic study should not be administered within 1 hour of enema administration. Evacuation of the gastrointestinal tract should be as atraumatic as possible, especially when working with an acutely ill patient. When an enema is contraindicated because of the poor condition of the patient, it is usually sufﬁcient to fast the animal. However, if fasting would compromise the patient's health further, mild, nongranular nourishment such as baby food or other commercially available foods (e.g., Hill's a/d, Clinicare) can be given. Many special radiographic procedures require sedation or anesthesia. Use caution so that the procedure is not compromised by the anesthetic. For example, general anesthesia is contraindicated for a gastrointestinal study due to subsequent slowed motility. If sedation is necessary, it should be limited to the use of a phenothiazine tranquilizer such as acepromazine maleate. Phenothiazine tranquilizers have only minimal effects on gastrointestinal motility or transit time. The use of parasympatholytic agents such as atropine should also be avoided for certain studies because of their anticholinergic effect.

Describe how x-rays are produced

X-rays are defined as a form of electromagnetic radiation similar to visible light but of much shorter wave-length. Electromagnetic radiation is a method of transporting energy through space and is distinguished by its wavelength, frequency, and energy. Essentially, there are two characteristics of electromagnetic radiation: particles and waves. X-rays are generated when fast-moving electrons (small particles bearing a negative charge) collide with any matter. This is best achieved in an x-ray tube. The x-ray tube consists of two electrodes, a cathode and an anode, that have opposite electrical charges. Because electrons have a negative charge at the cathode, they are attracted to the positive pole (anode) in the tube, and they collide with the positively charged target. This collision results in the production of x-radiation and a great amount of heat. Heat is the result of the interaction of the electrons and the atoms in the target. In fact, in diagnostic x-ray tubes, 99% of the energy from fast-moving electrons is converted into heat and 1% into x-ray energy. Key points 1. Energy travels in waves, the length of which is measurable. 2. X-rays with a shorter wavelength have a higher frequency and penetrate farther than rays having longer wavelengths. 3. X-radiation is a form of electromagnetic radiation produced when electrons moving with great speed collide with matter. 4. The ability of x-rays to excite and ionize molecules within cells can cause severe damage or death to those cells. 5. The first written report concerning x-rays and their use for medical and surgical diagnosis was made in 1895. The author and discoverer was Wilhelm Roentgen.

Compare and contrast the structure of the stomach and large intestines of carnivores and herbivores

function for both stomachs are the same: breaks down large molecules (such as from food) to smaller ones so that they can eventually be absorbed from the small intestine; can produce and secrete about 2 to 3 liters of gastric acid; absorbing some ions, water, and some lipid soluble compounds such as alcohol, aspirin, and caffeine; simply a food storage cavity carnivore/simple stomach: roughly j-shaped; essentially a large, dilated tube with 6 regions: esophageal region (most cranial and contain cardia), cardia (contains mucous glands that secrete mucus but not digestive enzymes), fundus (forms bulk of stomach, contains most of the gastric glands that produce digestive gastric juices which contains large amounts of HCl and pepsin (digestive enzyme) that begins breakdown of protein; lining of stomach secretes a thick layer of mucus that protects it from harsh acid and pepsin), body (distensible area situated in middle portion of stomach), antrum, and pyloric antrum (muscle sphincter, the pylorus, which helps regulate the passage of food from stomach into small intestines) compound/ruminant stomach: swallow their food and regurgitate it back thru esophagus into mouth to chew on it again (called rumination); different because it is designed to digest plant material; have 1 stomach with four chambers-- 1.reticulum; smallest; mucosa has a honeycomb pattern of folds that function to increase surface area and provides greater area for absorption of nutrients 2.rumen:largest part of forestomach; takes up most of left side; most important. part of ruminant stomach because where fermentation occurs (bacteria enzymes act on plant material to break down the polysaccharide cellulose--the primary part of plant fiber-and volatile fatty acid, proteins, and vitamins are produced that can be used) 3.omasum: ball-shaped cavity with numerous muscular folds; VFAs not absorbed in rumen are absorbed in omasum; bicarbonate ions and some moisture are removed from ingesta 4.abomasum; known as "true stomach" and very similar to simple stomach in organization and function; first 3 chambers called forestomach

Discuss why replacement drugs are often necessary for animal health

If an animal has a system that is failing or it was born with a defect of a system, it will need replacement drugs to maintain homeostasis for the rest of its life. Animals without properly functioning thyroids need replacement drugs to maintain homeostasis and have a good quality of life. Animals with diabetes need assistance of insulin to maintain proper blood sugar levels. Pharmacokinetics is the complex sequence of events that occurs after a drug is administered to a patient (Figure 1-1). Once a drug has been given, it is available for absorption into the bloodstream and delivery to the site where it will exert its action. After a drug is absorbed, it is distributed to various ﬂuids and tissues in the body. It is not enough for the drug simply to reach the desired area, however. It also must accumulate in that ﬂuid or tissue at the required concentration to be effective. Because the body immediately begins to break down and excrete the drug, the amount available to the target tissue becomes less and less over time. The veterinarian then must administer the drug repeatedly and at ﬁxed time intervals to maintain the drug at the site of action in the desired concentration. Some drugs are administered at a high dose (loading dose) until an appropriate blood level is reached. Then the dose is reduced to an amount that replaces the amount lost through elimination. Doses of other drugs are at the replacement level throughout the regimen. The point at which drug accumulation equals drug elimination is called the steady state. Underdosing leads to less-than-effective levels in tissue, and overdosing may result in toxic levels. Drug levels can be measured in blood, urine, cerebrospinal ﬂuid, and other appropriate body ﬂuids to help a veterinarian determine whether an appropriate level has been achieved. This procedure, which is called therapeutic drug monitoring, is being used increasingly in veterinary practice. Nonsteroidal antiinﬂammatory drugs (NSAIDs), cardiac drugs, anticonvulsants, and thyroid drugs are commonly monitored. The primary factors that inﬂuence blood concentration levels of a drug and a patient's response to it include the following: 1. Rate of drug absorption 2. Amount of drug absorbed 3. Distribution of the drug throughout the body 4. Drug metabolism or biotransformation 5. Rate and route of excretion

Discuss the properties of x-rays

The physical properties of x-ray electromagnetic radiation, listed as follows, have diagnostic, medical, and research applications: 1. Wavelength is variable and is related to the energy of the radiation. 2. Travel is in a straight line. Direction can be altered, but the new path is also in a straight line. 3. Because of the extremely short wavelength, x-rays can penetrate materials that absorb or reflect visible light. They are gradually absorbed the farther they pass through an object. The amount of absorption depends on the atomic number, the physical density of the object, and the energy of the x-rays. 4. Certain substances have the property of fluorescence (i.e., they can emit visible light). Crystalline substances such as calcium tungstate or rare-earth phosphors fluoresce (emit light) within the visible spectrum after absorbing electromagnetic radiation of a shorter wavelength (i.e., x-rays). 5. X-rays produce an invisible image on photographic film that can be made visible by processing the film. 6. X-rays have the ability to excite or ionize the atoms and molecules of the substances including gases through which they pass. Excitation is a process in which an electron is moved to a higher energy level within the atom. Energy is required to initiate this change. Ionization is a process in which an outer electron is completely removed from the atom so that the atom is left positively charged. This process requires more energy than excitation. 7. X-rays can cause biologic changes in living tissue. A biologic change occurs either by direct action of excitation and ionization on important molecules in cells or indirectly as a result of chemical changes occurring near the cells. Affected cells may be damaged or killed.

Discuss the function of the urinary system

The urinary system is made up of: • Two kidneys that make urine and carry out other vital functions • Two ureters that carry urine to the urinary bladder • One urinary bladder that collects, stores, and releases urine • One urethra that conducts urine from the body. Some by-products are of no further use and may actually be harmful if allowed to accumulate. These potentially harmful substances are called waste products and must be eliminated from the body. Some examples of metabolic waste products are: • Carbon dioxide and water from carbohydrate and fat metabolism • Nitrogenous wastes, primarily urea, from protein metabolism • Bile salts and pigments from red blood cell breakdown. • Various salts from tissue breakdown and excess intake The body has several routes by which waste products can be eliminated from the body: • The respiratory system removes carbon dioxide and water vapor. • The sweat glands eliminate water, salts, and a small amount of urea. • The digestive system removes bile salts and pigments. • The urinary system removes urea, salts, water, and other soluble waste products. The urinary system is the single most important route of waste-product removal in the body. It removes nearly all the soluble waste products from blood and transports them out of the body. The urinary system is also a major route of elimination for excess water in the body. Maintaining homeostasis in the body is the most important overall function of the kidneys. If the body needs to conserve water, less urine will be produced; and the animal will pass little urine (oliguria) or no urine at all (anuria). A kidney is made up of hundreds of thousands of microscopic ﬁltering, reabsorbing, and secreting systems called nephrons. The nephron is the basic functional unit of the kidney. The three main mechanisms by which the kidneys carry out their waste elimination role are ﬁltration of the blood, reabsorption of useful substances back into the bloodstream, and secretion of waste products from the blood into the tubules of the nephron.

Describe other diagnostic technologies used in veterinary medicine

Ultrasonography has been an important imaging modality in veterinary medicine since the 1980s. Ultrasound can provide information about organ architecture independent of organ function. It is especially helpful in debilitated or young patients, in which the contrast agents used in special procedures or exploratory surgery may be contraindicated. Ultrasonographic ﬁndings are not necessarily speciﬁc for histopathologic diagnoses. However, the ability to distinguish solid masses from those containing fluid and to determine the distribution of lesions in organs allows the sonographer to focus differential diagnoses and to formulate management plans. COMPUTED TOMOGRAPHY or CT, which is available at most academic institutions and in some veterinary specialty practices, is one of the most expensive diagnostic tests in veterinary medicine. Its major advantage is the ability to acquire information not available from radiographs, contrast studies, or ultrasound examinations. The primary indications for CT are central and peripheral nervous system diseases of the brain, spinal cord, and lumbosacral spine. It is also useful for obscured masses in the mediastinum, axillary region, and retroperitoneal space. Nuclear scintigraphy is a noninvasive imaging procedure that uses a small amount of radioactive material (radio-nuclide) administered intravenously, transcolonically, or by aerosol insufflation. Scintigraphy is more sensitive but less speciﬁc than standard radiographs or CT. Images do not provide the anatomic detail of radiographs or CT, but they do provide physiologic information about the function of speciﬁc organs. The studies are complementary to those of other imaging modalities.

Properly position for routine small-animal radiographs

Understanding the correct terminology for the various anatomic views is essential to a radiographer. The directional terms cited in this text are based on the revised terminology system advocated by the American Committee of Veterinary Radiologists and Anatomists. This relatively new system exactly deﬁnes the position and direction of the primary x-ray beam. The correct veterinary anatomic directional terms and abbreviations for radiographic projections follow. Left (L) Dorsal (D) Right (R) Ventral (V) Medial (M) Lateral (L) Cranial (Cr) Rostral (R) Caudal (Cd) Palmar (Pa) Oblique (O) Plantar (Pl) Care must be taken to include all essential anatomic regions in the primary beam when positioning patients. The primary goal of positioning for radiography is to ﬁnd the most suitable posture to produce an accurate reproduction of the anatomic area. Several important factors must be considered if an accurate reproduction is to be made: 1. Welfare of the patient 2. Restraint and immobilization of the patient 3. Minimal trauma to the area of interest 4. The least risk of exposing those assisting with the examination to radiation. Because a radiograph is a two-dimensional picture of a three-dimensional structure, two views of each anatomic area taken at right angles to each other are the minimum recommended. The importance of two views is exempliﬁed when radiographing a fractured bone. For example, one view of a nondisplaced oblique fracture of a long bone may appear normal. Both a lateral and a craniocaudal view would be necessary to visualize the fracture line. Another guideline is to position the area of interest closest to the ﬁlm. This reduces distortion and magniﬁcation of the area under examination. In addition, if a limb is being radiographed, it may be helpful to radiograph the opposite corresponding limb. This allows the pathologic structure of one leg to be compared with the normal anatomy of the other. In general, the central x-ray beam should be centered directly over the area of interest. For example, if the x-ray beam is centered over the caudal border of the thirteenth rib for a study of the abdomen, the entire abdomen is included (assuming the proper-size cassette is used). The measurement for any anatomic region should be taken over the thickest area. This ensures that all regions of the part of interest will be penetrated with sufﬁcient exposure factors. Speciﬁc anatomy must be included for each anatomic area. For example, all radiographs of long bones (humerus and femur) should include the shaft of the bone, as well as the joints both distal and proximal to the bone. For joint radiography, the x-ray beam must be centered over the joint space, and the beam should include a portion of the long bones distal and proximal to the joint.

Read the information found on drug labels and package inserts

You will need to understand the information found on drug labels in order to calculate drug dosages. 1. Name of drug: Mycobutin is the trade name. In this case, the name begins with an uppercase letter, is in large type, and is boldly visible on the label. The generic name is rifabutin, written in lowercase letters. 2. Form of drug: The drug is in the form of a capsule. 3. National Drug Code ( NDC) number: 0013- 5301- 17. 4. Bar code: Has the NDC number encoded in it. 5. Dosage strength: 150 mg of the drug are contained in one capsule. 6. Dosage recommendations: 2 capsules in a single daily administration. Note that the manufacturer informs you to read the package insert. 7. USP: This drug meets the standards of the United States Pharmacopeia. 8. Storage directions: Some drugs have to be stored under controlled conditions if they are to retain their effectiveness. This drug should be stored at 25° C ( 77° F). 9. Expiration date: The expiration date specifies when the drug should be discarded. After 10/ 2013 ( October 31, 2013), the drug cannot be dis-pensed and should be discarded. For the sake of simplicity, not every drug label in this textbook will have an expiration date. 10. Manufacturer: Pharmacia & Upjohn.

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