Heartworm Flashcards
(33 cards)
How long is the life cycle of heartworm?
184-210 days (6-7 months)
what stage of heartworm is transmitted from the mosquito to the dog?
L3
where is heartworm maturation completed?
PA
at what point does a HWI turn progress to HWD?
when worms get into the vasculature and cause damage to the pulmonary aa.
within the pulmonary aa. what might heartworms induce?
inflammation, endothelial damage, myointimal proliferation, disruption of vascular integrity, fibrosis, and pulmonary hypertension
what type of congestive heart failure might heartworm lead to?
R-sided!
structural changes to lumen of pulmonary aa. and vasoactive substance from worms > increased PVR > increased PAP > increased RV & RA pressure > tricuspid regurgitation
how does heartworm cause thrombosis?
structural changes to lumen of pulmonary aa. and vasoactive substance from worms > increased PVR > increased afterload on RV > decreased CO > decreased pulmonary arterial flow
what can lead to pulmonary parenchymal dz in dog with heartworm?
inflammatory immune response of host, increased vascular permeability, PTE, eosinophilic pneumonitis and granulomatosis
what is wolbachia?
intracellular, gram-negative bacteria that lives in D. immitis
what drug is used in heartworm treatment to reduce or eliminate wolbachia?
doxycycline
mechanical obstruction (by worms) of blood flow in the R. side of the heart & vena cavae leading to hemolytic anemia and cardiogenic shock
caval syndrome
T/F: cats more commonly have aberrant migration of heartworm (neuro, muscular, ocular, systemic aa.)
TRUE, cats are unnatural host
what clinical signs might you see in a dog with heartworm dz?
exercise intolerance, wt loss, lethargy, cough, tachypnea, dyspnea, hemoptysis, R-CHF signs, syncope or collapse, hematuria (hemoglobinuria)
what heart abnormalities might you find in a dog with heartworm dz upon physical exam?
split S2, murmur due to tricuspid regurg, gallop
T/F: the test of choice in diagnosing HWD in dogs is an antibody test and cats is the an antigen test
FALSE, opposite
cats don’t often get adults (false - more common in antigen test)
what does the antigen test detect in diagnosing HWD?
Ags in reproductive tract of adult female
what are the four main treatments you should do for dog with HWD?
1) macrocyclic lactone preventatives
2) doxycycline
3) exercise restriction
4) adulticide therapy with melarsomine dihydrochloride
what macrocyclic lactone preventative is contraindicated in microfilaremic dogs?
milbemycin (potent and can cause anaphylaxis)
what stages of HW do macrocyclic lactone preventatives reduce or eliminate?
microfilaria, L3, and L4
why is exercise restriction so important in treating HWD?
reduces risk of thromboembolic complications
what protocol should you use when treating a dog with HWD and why?
3-dose (“split-dose”) protocol with melarsomine dihydrochloride
less dramatic worm death and therefore less risk of post-adulticidal complications
why is the “slow-kill” method of macrocyclic lactones contraindicated?
takes too long! ongoing damage to pulmonary aa. and lungs
prevention and treatment of adverse rxns to microfilaricides, penumonitis, pulmonary granulomas, PTE, and analgesia for melarsomine injections are all reasons to use what drug in a dog with HWD?
corticosteroids
other than a corticosteroid what other drug might you consider giving a microfilaric dog before conducting microfilaricidal therapy?
diphenhydramine
