Heartworm disease Flashcards
What is the life cycle of dirofilaria?
- mosquito ingests microfilariae
- L3 stage transmitted to animal
- develops to L4 stage and migrates to lungs to mature
- adult females produce microfilariae
When is a patent infection of dirofilaria noticeable?
6-9 months post-infection in dogs
What are the clinical signs of heartworm infection?
- cough
- exercise intolerance
- dyspnea
- abdominal distension
- syncope
- weight loss
What is found on physical exam of heartworm infection?
- right-sided murmur
- split S2
- arrhythmia
- pulmonary crackles
- ascites
How do you diagnose heartworm?
- antigen test that detects antigen released by female dirofilaria (can have false negatives)
- microfilariae test that distinguishes dirofilaria from A. reconditum (can be - in Ag+ dog)
- thoracic radiographs
What is seen on thoracic radiographs of heartworm?
- main pulmonary artery enlargement
- RV enlargement
- enlarged and tortuous pulmonary arteries
- interstitial to alveolar pattern
- right-sided CHF
What is involved in adulticide therapy for heartworm?
- melarsomine
- 2 injection protocol (2 IM injections, 24h apart)
- 3 injection protocol (1 IM injection, wait a month, 2 IM injections 24h apart)
What is involved in the adjunctive therapy for Wolbachia in heartworm infections?
- intracellular bacteria found in D. immitis
- use doxycycline, which decreases the inflammatory response associated with worm death
What other adjunctive therapy for heartworm is there?
- steroids to decrease inflammation associated with pulmonary thromboembolism
- preventatives against younger larvae
What are macrocyclic lactones?
- preventative therapy administered 2-3 months prior to adulticide therapy (eliminates larvae <2mo)
- decreases circulating microfilariae
What is caval syndrome?
migration of worms from arteries to vena cava and right atrium
What is essential to a good recovery from heartworm?
exercise restriction
What are some complications that can arise from heartworm infections?
glomerulonephritis
- right-sided heart changes and CHF
- caval syndrome
- sudden death
What are the clinical signs of caval syndrome?
- severe lethargy
- dyspnea
- pale MM
- weakness
- hemoglobinuria
- right-sided systolic murmur
When should you re-test for heartworm?
antigen test 6 months after treatment
What is important to know about feline heartworm disease?
- worm maturity not necessary to cause pathology
- lower worm burden
- male-only infection
What are the two stages of development of feline heart heartworm?
- arrival to pulmonary vasculature
2. death of adult worms
What is heartworm associated respiratory disease (HARD)?
- inflammatory disease that correlates with arrival of worms to lungs
- results in asthma-like signs, so test all gouging cats for heartworm
How do you diagnose feline heartworm disease?
- antibody test (doesn’t indicate active infection)
- antigen test (false negatives)
- thoracic radiographs
- microfilaremia
How do you treat feline heartworm disease?
- prevent the infection, although melarsomine is CONTRAINDICATED
- treat symptoms
