Chapter 58 - Heartworm disease

Question 1

What are the most important manifestation of heartworm disease in dogs?

Answer 1

1. Respiratory distress (pneumonitis and/or pulmonary thromboembolism)
2. Right sided congestive heart failure (due to severe PHT)
3. Caval syndrome

Question 2

What are the most important manifestation of heartworm disease in cats?

Answer 2

1. Asthma-like signs due to heartworm-associated respiratory disease (HARD)
2. Anaphylaxis-like reaction (due to worm death)
3. Rarely right sided CHF
4. Rarely caval syndrome

Question 3

What makes feline HW differs from canine HW?

Answer 3

1. Most cats clear the majority of immature adults prior to their maturation
2. Due to the low number of adult heartworms and immune-mediated clearance, most cats have few or no circulating Mf and only transient microfilaremia.
3. Aberrant migration of worms to ectopic sites has been described in dogs and cats, but may be more common in cats.

Question 4

Where are D.immitis usually found?

Answer 4

Distal pulmonary arteries, with the right caudal lobar artery accumulating the most worms.

Question 5

What is Cor Pulmonale?

Answer 5

PHT (causing right ventricular pressure overload) can lead to right-sided heart disease.

Question 6

Why do we use doxycycline for heartworm?

Answer 6

D.immitis harbors the gram negative bacterium Wolbachia, which is susceptible to doxycycline. D.immitis need this symbiotic organism for normal development, reproduction, and survival of all stages.

Question 7

Radiographic signs of heart worm in dogs?

Answer 7

RV hypertrophy, dilation of MPA, dilation of branch pulmonary arteries, pulmonary parenchymal infiltrates, hepatomegaly, ascites.

Question 8

T/F: lasix is indicated in eosinophilic pneumonitis

Answer 8

False: inflammatory infiltrates in perivascular tissue can cause perivasular edema, but this is not a cardiogenic edema and lasix is not indicated.