E3: Local Anesthesia Techniques for Cattle

How do you find the space where the needle is to be inserted for an epidural?

(After clip and surgical wash) 1. Grasp the tail near the base and move it up and doan like a pump until you can feel the sacrocaudal or first intercaudal space when placing your finger in the indentation and feeling it being pinched in these spaces 2. Once on you decide on which space to you lower the tail so the space is open 3. Place the needle in the midline of this space nearly perpendicular but slightly cranially directed

How much lidocaine is used for a cornual nerve blockÉ What size and gauge of needle to we needÉ

-10 - 15 ml -16 - 18 gauge 1-1.5 inch needles

Onset time for a cornual block is __-___ minutes and the duration is about __ ______

-10-15 minutes -one hour

What size and gauge of needle is used for an inverted L block? Approximately ___-___ml is injected slowly at each needle poke.

-18 g 1.5 inch needle -10-15 ml

What gauge and length of needle do we use for the distal paravertebral lumbar block? How about the proximal paravertebral lumbar block?

-18 g 3-4 inch needle -16-18 g 4-6 inch needle

What size needle and syringe are needed to give a cow an epidural?

-6 cc syringe -18 guage 1.5 inch needle

Where do we inject for a cornual nerve blockÉ

-Approximately 1 inch anterior to base of horn and lateral to the temporal bone (Halfway between the base of horm and the lateral canthus of the eye) -Sometimes a second injection is needed in adult cattle with well developed horns, either in a line about half an inch behind the horn base or as a ring block

What nerves does the distal paravertebral lumbar nerve block desensitize? Where are the injection sites?

-Block T13 -L1 -L2 (same as the proximal block) -Inject at the lateral ends of the transverse processes of vertebrae L1, L2 and L4

What species is very susceptible to problems with too much lidocaine so we do not give more than ___ ml of a ___% lidocaine solution

-Goats -10ml -2%

In an inverted L block it is important that the lidocaine is not injected too near the proposed ______ _____, why?

-Incision site -Because lidocaine can interfere with wound healing, as well as causing local edema from the irritation

How do you inject the lidocaine at a site for an inverted L block? Why do we do it this way?

-Inject a few cc's of lidocaine at the deepest point then inject remaining lidocaine as you draw the needle out. - So all layers get anesthestized

For the proximal paravertebral lumbar nerve block in order to desensitize T13 we inject our lidocaine at ____. In order to densensitize L1 we inject at ___. In order to densensitize L2 we inject at ____.

-L1 -L2 -L3

When using lidocaine in calves what must we be careful of? What are symptoms? How do we avoid this?

-Not to give too much or toxicity can occur -Restlessness, muscle fasciculations and seizures (also drop in BP) -To avoid dilute 2% solution with sterile saline to make a 1% solution to avoid potential problems

How do you direct the needle when giving a cow an epidural?

-Push needle into proper location nearly perpendicular but directed slightly cranially. Make sure you are directly on the midline

How can you tell you are in the epidural space?

-Should feel a pop when you pierce the dorsal ligament and then if there is any lidocaine in the hub of the needle it will be sucked into the epidural space (also there should be no resistance when injecting)

What layers are infiltrated and anesthetized in an inverted L block? How long does it take for the nerves to be desensitized after the injection? How long is the duration?

-The skin and the full thickness of the body wall (muscle, peritoneum) -10 -15 minutes after -lasts 1-2 hours

How can you tell if yuor epidural block worked? How long do you wait for there to be sufficient anesthesia for surgery?

-The tail will become flaccid within 1-2 minutes of injection -10 minutes

What is the cornual nerve block used forÉ

-non cosmetic and cosmetic procedures (dehorning)

An epidural provides temporary local anesthesia in the _______ region of cattle that lasts approximately ____ to ______ hours

-posterior -1-1.5 hours

Sometimes a ______ injection is needed in ___ cattle with ____ _______ horns, either in a ____ about half an inch behind the horn base or as a ____ block

-second -adult -well developed -line -ring

For the distal paravertebral lumbar block we insert the needle _______ to the transverse process and inject ___ml _________, ____ ml _________ and ___ml ________ in this area (fan wise) about ____ inch deep from the _____ of the transverse process. We then withdraw the needle slightly and redirect _____ to the transverse process and inject ___ml there.

-ventral -5ml -centrally -5ml cranially -5ml caudally -half an inch -ends - dorsal - 5ml

In the Proxinal Paravertebral Lumbar Nerve Block we _____ ____ the needle from the _____ edge of the transverse process and insert half an inch deeper to deposit __ ml (which desensitizes the _____ branch). We then withdraw the needle slightly and redirect the needle ______ to the half an inch below the transeverse process and deposit another ___ ml. We again withdraw the needle redirect ______ and deposit an additional ___ ml again at a half an inch below the transverse process. We then withdraw the needle and find the ____ landmark, bring the needle ___ a half an inch _____ the transverse process and depost an additional ___ ml (this desensitizes the ____ branch)

-walk off -cranial -5 ml -ventral -medially -5 ml -laterally -5 ml -bone -up -above -5 ml -dorsal

What is the disadvantages of the Proximal Lumbar Nerve Anesthesia compared to the Inverted L Block (4)

1. A special needle is required 2. Takes a bit of practice 3. Must clip hair over the dorsal spinal column 4. Possibility of penetrating vital structures (aorta and thoracic longitudinal vein on the left abdomen side and the caudal vena cava on the right side)

Why do we perform local nerve blocks of the lower equine limbs (3)

1. Because sometimes its difficult to localize the exact site of lameness from just an exam, so diagnostic nerve blocks are used to temporarily desensitize a region to rule out a suspected problem area. 2. To provide analgesia for surgery in that region 3. To provide analgesia in a painful area

How can diagnostic nerve blocks for horses be doneÉ (2)

1. Blocking sensory nerves innervating specific regions 2. Injecting local anesthetic intra articularly

Describe how to prepare the lower equine limb for a local block

1. Clip injection area 2. Do a surgical scrub and rinse with alcohol

How do you prep a cow for an epidural?

1. Clip the area over the tailhead 2. Do a surgical wash and after the rinse apply isopropyl alcohol

List some common indications for performing an epidural on cattle

1. Dystocia 2. Perineal surgeries (Scrotal surgeries, prolapse repair) 3. Penile urethrostomy

What are the three methods used to obtain regional anesthesia of abdomen? What are these blocks used for? (3)

1. Inverted L Block 2. Proximal Paravertebral Lumbar Nerve Anesthesia 3. Distal Paravertebral Lumbar Nerve Block

What is the advantages of the Proximal Paravertebral Lumbar Nerve Anesthesia over the Inverted L Block (3)

1. Less local anesthetic needed 2. A wider area of analgesia is produced 3. Lidocaine is not in the incision area so cannot interfere with healing

What are the three drugs of choice for equine lower limb local nerve blocksÉ

1. Lidocaine 2. Bupivicaine 3. Mepivicaine

List the five different kinds of lower equine limb local nerve blocks

1. Palmar Plantar digital block 2. Ringblock distal to fetlock 3. Abaxial sesamoidean block 4. Four point dorsal to the fetlock joint 5. High palmar block

What are the two injection sites for epidurals in cows?

1. Sacrocaudal space 2. Intercaudal space

What two things does the amount of lidocaine required in a inverted L block depend on?

1. Size of the animal 2. Anticipated size of the incision

List three possible complications from local nerve blocks of the lower equine limbs

1. Swelling and irritation from the anesthetic agent 2. Infection from dirty injection technique 3. No effect due to accidental intravascular injection

How do you prep a cow for a c-section?

1. Use large animal clippers to prep a wide area for the c-section 2. Take small animal clippers and clip a smaller vertical rectangular area 3. Do a surgical scrub starting with the middle of the small rectangle as the primary area and working outwards, rinse and repeat three times, finish with isopropyl alcohol

What size needles are used for lower equine limb nerve blocks

21 - 25 g 0.5 -1 inch (finer gauge needles are usually used for the most distal nerves

In what direction do you insert the needle when you are injecting at a site for the inverted L block

At a 45 degree angle pointing towards the ground

Where do we prep for the distal paravertebral block?

Clean and scrub the skin at the ends of the transverse processes

Where does the palmaréplatnar digital nerve block desensitize

Desensitizes the posterior foot

T or F It is important to clip and scrub around the horn before performing a cornual block

F (Only if have a cosmetic dehorning then a surgical prep is needed)

__________ __________ of the spine towards the anesthetized saide will be noted due to paralysis of the paravertebral muscles on the blocked side. Also the skin will feel _______ on the blocked side due to _________.

Lateral curvature -warmer -vasodilation

Where is the injection site for the proximal paravertebral lumbar nerve blockÉ

Lateral to and halfway from the midline to the end of the transverse process of L1, L2, and L3

Does the inverted L block interfere with ambulation?

No

How deep is the nerve for the cornual nerve blockÉ

Superficial (quarter to half an inch deep)

What nerves are blocked with a proximal paravertebral lumbar nerve blockÉ

T13, L1, and L2 (with one more injection L3 can also be blocked)

Which block is harder to perform on fatter animals?

The distal paravertebral lumbar nerve block

Where does the four point nerve block desensitizeÉ

The entire fetlock region and everything distal to it

What happens if too much lidocaine is given in an epidural?

The legs will be temporarily paralyzed

What happens if when performing an inverted L block you inject too much lidocaine in each site?

The skin dries and hardens and may even slough off in those areas over the next couple of weeks

Where does the Abaxial sesamoidean block desensitize

most of the strucutrs distal to the fetlock except for the proximal dorsal surface below the fetlock

Where does the ringblock distal to fetlock desensitizeÉ

the entire pastern and foot