Parasitology - Heartworm

Caval syndrome is developed in ___ - ___ % of dogs with heartworm disease. Clinical signs include _____ distress (which can cause sudden collapse), weakness, _____, and hemoglobinuria.

- 16 - 20% - Respiratory - Ascites

The L3 will then moult from L3 to L4 in ___ - ___ days. And then they will moult again from L4 to L5 in ___ - ___ days.

- 2 - 4 - 50 - 70

Less than _____% of cats have microfilaria because the microfilaria don't live as long.

- 20%

_____% of dogs with circulating microfilaria may develop adverse reactions if treated with DEC.

- 25%

Aprroximately _____% of dogs with heartworm infection are amicrofilaremic. Must be diagnosed with _____ or ELISA (HW antigen test). _____ antigen concentrations correlate to the number of adults.

- 25% - IFA - Serum

When using Clin-Path to diagnose a cat, since less than 20% of cats have microfilaria, you need to run 3-4 tests using _____ mL of blood.

- 5

Cats are 20% more susceptible to _____ than dogs.

- Arsenic

Treatment for heartworms is extremely _____ and can be toxic to the _____ and _____.

- Dangerous - Liver - Kidneys

What is a daily HW preventative?

- Diethylcarbamazine (DEC) - Can also be used as treatment of roundworms, hookworms, and whipworms.

Four methods used to demonstrate the presence of heartworm microfilaria? Solutions? Concentration methods? Motility?

- Direct Exam (Motility) - Buffy Coat Test - Filter Test (Lysing solution, Con) - Modified Knotts (2% Formalin, Con)

What are some ways that you can diagnose heartworm disease?

- Direct Smear - Modified Knott's Test - Filter Test - Buffy Coat Test - HW antigen/antibody ELISA (need 3 adult female HW - not used for microfilaria) - Enlarged right heart in radiographs - ECG - CBC (basophils and eosinophils)

What is the specific type of heartworm called?

- Dirofilaria immitis

Heartworm treatment: Day 271?

- Do some AG testing 6 months after completion.

Heartworms cause damage to the _____ of the pulmonary arteries. Most arteries will form _____ along the lumina of the vessels. In smaller vessels, _____ lesions can form due to inflammation. Killing high numbers of microfilaria all at once can cause _____.

- Endothelium - Lesions - Obstructive - Anaphylaxis

Some clinical signs of heartworm include _____ intolerance, _____ cough due to blockage, enlarged _____, dyspnea, and heart murmur.

- Exercise - Chronic - Liver

Before starting treatment, the dog must be diagnosed and verified as HW+. If HW+, begin _____ restriction. If the dog is showing any symptoms, go ahead and treat with _____.

- Exercise - Prednisone

The heartworm is considered as a _____ worm which occurs frequently in dogs, rarely in cats, and ferrets.

- Filaroid (nematode)

Selamectin (Revolution) is a monthly HW preventative that is also used in the treatment of _____, mites, and ticks. However, this drug has no _____ parasite control in the dog.

- Fleas - Internal

Heartworm treatment: Day 1-28?

- Give Doxycycline. It reduces Wolbachia, reduces the pathology due to dead HWs, and disrupts HW transmission.

Heartworm treatment: Day 30?

- Give HW preventative macrocyclic lactone.

Heartworm treatment: Day 60?

- Give HW preventative macrocyclic lactone. - Give first adulticide treatment (melarsomine)

Heartworm treatment: Day 90?

- Give HW preventative macrocyclic lactone. - Give second adulticide treatment (melarsomine)

Heartworm treatment: Day 1?

- Give the HW preventative macrocyclic lactone and continue for 2-3 months. If microfilaria are present, pretreat with antihistamines and steroids (if not on prednisone) to reduce the risk of anaphylaxis. Observe the dog for 8 hours for signs of a reaction.

Heartworm treatment: Day 91?

- Give third adulticide treatment (melarsomine) - Continue exercise restriction for 6-8 weeks.

The major result of pulmonary artery obstruction is pulmonary _____. This can cause _____ cardiac output, _____ workload of the right ventricle, and right heart _____.

- Hypertension - Increased - Increased - Failure

Occult Heartworm Disease may be due to what 5 situations?

- Immature adults - Adults are once sex - Ectopic adults - Immune system kills microfilaria but not adults - Monthly preventatives are microfilaricidal and prevent the release of new microfilaria.

The microfilaria is then injested by the _____ host, which is the _____.

- Intermediate - Mosquito

What are some monthly HW preventatives?

- Ivermectin (oral) - Milbemycin oxime (oral) - Selamectin (topical) - Moxidectin (topical and subQ)

Once inside the mosquito, the microfilaria will develop into infective _____ larvae in _____ weeks. This will only happen if the temperature is above _____ degrees.

- L3 - 2 - 70

With Feline HW Disease, the % of infective larvae that develop into adult worms is _____, the adult burdens are _____, the lifespan is shortened (___ years), and the prepatent period is _____ (___ months).

- Less - Less - 2 Years - Longer - 8 months

Adult females will hatch fertilized eggs in the uterus, and will also discharge _____ into the _____, where they can remain active for up to _____ years.

- Microfilaria - Bloodstream - 2

When diagnosing a cat for HW, the ELISA antigen test may be _____ due to the low # of females, and low test sensitivity.

- Negative

The L5 will migrate to the _____ arteries/_____ heart, and mature to adults in ___ - ___ months.

- Pulmonary - Right - 3 - 4 months

With Feline HW Disease, cats are more _____ than dogs.

- Resistant

Ivermectin is a monthly HW preventative that is also used in the treatment of _____ and _____.

- Roundworms - Hookworms

Milbemycin oxime (Interceptor) is a monthly HW preventative that is also used in the treatment of _____ and _____. Can also be used as a _____ preventative.

- Roundworms - Whipworms - Flea

The L3 larvae then migrate to the mosquito's _____ _____, where they will enter the new host once the mosquito feeds.

- Salivary Glands

What is a Feline HW Disease treatment?

- Selamectin - Ivermectin - Moxidectin + Imidacloprid

You can use _____ testing in cats for Feline HW Disease. The preferred screening lab test is ELISA HW _____ test.

- Serology - Antibody

With feline HW, the risk of complications is more _____ in cats than dogs because they are very susceptible to _____.

- Severe - Thromboemboli

Adult heartworms die _____ over a period of days to several weeks. They are carried by pulmonary arteries to the _____, where they will lodge and temporarily obstruct circulation until they are removed by _____.

- Slowly - Lungs - Phagocytosis

The dog must not be _____ during treatment, and should be put on bed rest for ___ - ___ weeks. After this time period, the liver and kidney should be reevaluated.

- Stressed - 4 - 6 weeks

Once inside the final host, the L3 will travel to the _____ space, muscle, or _____ tissue.

- SubQ - Connective

Moxidectin (Proheart) is a monthly or 6 month HW preventative. It can be given as a _____ injection and it is effective against _____ that may be present.

- SubQ - Hookworms

Caval syndrome may require _____ removal of heartworms from the _____ valve and right atrium.

- Surgical - Tricuspid

Heartworm treatment: Day 120?

- Test for microfilaria. - If positive, treat and repeat Doxycycline for 30 days. - Give HW preventative year-round.

What can be used to distinguish between Dirofilaria and Dipetalonema?

- The direct exam will show motility. Dipetalonema will be moving rapidly. - The filtration test will show differences in appearance. Dirofilaria are large and have a tapered head.

Adult heartworms can live up to _____ years.

5

In cats, you may not want to risk treatment because they will probably die either way, especially if HWs are in their heart for longer than _____ months.

6

Microfilaria appear in peripheral blood for the first time about ___ - ___ months after infection.

6 - 7 months

What is caval syndrome?

Adult heartworms in the right heart that have backed up into the vena cava. This is due to a heavy heartworm burden.

What can also cause obstructive and inflammation?

Dead Worm Thromboemboli

Most heart-worm infected dogs have no clinical signs at the time of _____.

Diagnosis

Damage to the host is caused by the _____ stage and adults.

L5

What adulticide is 90% effective, and is given deep IM into the lumbar muscles?

Melarsomine Dihydrochloride (Immiticide)

In Feline HW Disease, are cats the final definitive host?

No

What is Occult Heartworm Disease?

Presence of adult heartworms without circulating microfilaria.

Why should dogs on a monthly HW preventative be tested with a HW antigen test instead of a microfilaria test?

The monthly HW will kill the microfilaria, but not the adults. Therefore, the antigen test is used to detect the presence of adults.