Heartworm Disease Part I Flashcards
what is the definitive host of Dirofilaria immitis?
dog
what is the infective stage of Dirofilaria immitis?
L3 larvae
what is class I of heartworm disease?
evidence of disease absent or mild
usually identified by routine screening
what is class IV of heartworm disease?
caval syndrome
what is class III of heartworm disease?
severe heartworm disease
typically with cor pulmonale
“heartworm” is rpimarily a disease not of the hart but of the _____________________
pulmonary arteries
when do vascular changes occur with heartworm disease?
within 3 weeks of adult heartworm transplantation
what on pathology is pathognomonic of dirofiliriasis?
villous endarteritis
what is villous endarteritis?
proliferation of smooth muscle cells of tunica media
migration of smooth muscle cells to intima and production of villi
what is a common complication of adulticide therapy 1-3 weeks after treatment?
adult worm death catastrophic consequences
why can pulmonary thromboembolism occur with heartworm disease independently of worms?
platelet activation
endothelial damage
chronic inflammation
glomerulonephropathy
blood stasis
why can chronic pulmonary arterial disease result in cor pulmonale?
leads to pulmonary hypertension which leads to right ventricle pressure overload
this leads to right ventricle hypertrophy and right sided heart failure eventually
what do microfilariae sequestered in the lungs cause?
intense eosinophilic infiltration
what is happening in caval syndrome?
heartworms are present within the heart
what does eosinophilic infiltration from microfilariaee sequestered in the lungs look like on chest radiographs?
diffuse interstitial to alveolar infiltrates
can progress to granulomatous-type reactions- looks like metastases
what does caval syndrome require?
immediate surgical removal of adults
what can cause glomerular disease from heartworm disease?
immune-mediated glomerulonephropathy: immune complexes
low cardiac output
when can disseminated intravascular coagulation happen with heartworm disease?
endothelial damage with severe disease
caval syndrome
especially post-adulticide
what can increase the host immune response to Dirofilaria immitis?
Wolbachia organisms
what are Wolbachia organisms?
obligate, intracellular gram negative bacteria
critical for certain stages of filarial life cycle
what decreases pulmonary pathology associated with adulticide?
pre-treatment with doxycycline and ivermectin
what are aberrant heartworm infections characterized by?
ectopic migration of larvae
are cats resistant to heartworm disease compared with dogs?
yes: 10% or canine infection rate
how often are cats microfilaremic?
rarely
what is feline heartworm-associated respiratory disease often confused with?
feline asthma
what is important when considering a cat with heartworm compared to a dog?
cats have smaller pulmonary artery trees: embolizations, even small ones, can have disastrous effects
what are consistent findings of feline heartworm disease?
dyspnea and cough
what is class II of heartworm disease?
moderate disease with coughing and exercise intolerance but no heart failure
radiographic changes evident
what cells contribute acutely to pulmonary arterial disease?
neutrophils
eosinophils
what can adult worm death cause?
embolization: thrombosis, inflammatory
pulmonary infarction, acute R-sided CHF, respiratory failure, vascular rupture
why can pulmonary thromboembolism occur with heartworm disease?
death of adult worms: thrombus
hypercoagulable state
what can microfilariae sequestration in the lungs result in?
occult infections: no circulating microfilariae
where might adult worms be present in caval syndrome?
right ventricle
right atrium
vena cavae
hepatic veins
what does research show with Wolbachia organisms and heartworm disease?
targeting Wolbachia in addition to D. immitis may greatly decrease pathology and improve outcome
when might a systemic arterial thrombosis occur with aberrant heartworm infections?
if L5 stage migrates into arterial system
