Lecture 8 - Heartworms Flashcards
what are the hosts of heartworm
dogs, ferrets, sea lions, cats
T/F: more damage can occur to cats with heartworm infections because they are not a “good” host
TRUE
T/F: dogs older than 6 months old are susceptible to heartworm
FALSE - any age is susceptible
where do adult worms live
pulmonary artery
what is the intermediate host foe heartworms
mosquitoes
at what point in the lifecycle are heartworms infectious
L3
T/F: microfilariae are not L3s
TRUE
how long does it take for heartworms to mature in mosquitoes
10-14days
isoxazolines _____ mosquito survival after blood feeding
decrease
what is patency regarding heartworms
the time is takes for worms to mature and produce offspring in host (~`6-7 months post-infection)
when can tests detect heartworms
6 months post-infection
T/F: the # of adults in a host equals the # of microfilariae that infect the host
TRUE
T/F: heartworms have a shorter life cycle in cats
FALSE
what does aberrant migration of heartworms mean
migration to ectopic sites other than the pulmonary system
T/F: usually heartworm infections in cats are <5 worms
TRUE
how are cats infected with heartworm
bitten by mosquitoes that have fed on infected dogs
what does the severity of heartworm disease depend on
- # of adult worms
- duration of infection
- individual host response
T/F: heartworm disease is a multiple organ disease
TRUE
what are the 2 hallmarks of pulmonary arterial disease
- inflammation (endarteritis damage from friction of flow)
- villous thickening
what is the pathologic appearance of pulmonary arterial disease
roughened, stippled appearance
what does vessel thickening lead to
- loss of elasticity
- increased pressure
- R side enlargement, CHF w/ascites
what is Wolbachia
endosymbionts in filarioid nematodes
what is the role of Wolbachia in pathogenesis
associated proteins induce innate inflammatory response
what are the 3 stages of feline HWD
- worms reach lung vessels and induce an acute inflammatory response
- dying worms induce inflammation and thromboembolism
- chronic respiratory disease
what is HARD
heartworm-associated respiratory disease (stage 1 feline HWD) commonly mistaken for asthma
what are the 2 outcomes of stage 2 feline HWD
- acute lung injury
- sudden death
what is the outcome of stage 3 feline HWD
hyperplasia of alveolar cells
what is caval syndrome
large number of worms obstructs blood floe through the tricuspid valve and results in death within 12-72 hours
how is caval syndrome treated
surgical removal of worms via jugular v.
what are the symptoms of heartworm disease in dogs
- chronic cough
- dyspnea
- decreased exercise tolerance
- syncope
- hemoptysis
- CHF
what percentage of feline heartworm cases are completely indoor cats
33%
what are the symptoms of heartworm disease in cats
- V+ unrelated to eating
- lethargy, weight loss
- systolic heart murmur
- respiratory distress
- seizures, ataxia
- sudden death
what does the heartworm antigen test detect
female uterine antigen
what infections would not be detected with the antigen test
- single-sex infections (male)
- prepatent infection (<5months)
- low burden
ELISA is _____ or a lateral flow-based test
immunochromatographic
T/F: immunodiagnostic test is available for cats but less sensitive
TRUE
how do positive and negative results differ for a feline immunodiagnostic test
positive = has been infected before, but titers stay high after death
negative = not been infected (at least not recently)
T/F: a negative antigen test is definitive
FALSE
when should puppies be tested for heartworm
7-8 months of age
why should you microfilariae test
confirms positive antigen test and identifies reservoir of infection
direct smears detect ____ of patent infections
75%
knott’s test
spin/concentrate blood sample and then look
what is nonpathogenic, transmitted by fleas, but bears resemblance to MF of heartworms
A. (D.) reconditum
what is the appearance of heartworm microfilariae versus A. reconditum
heartworm = tapered tip
A. reconditum = blunt
pulmonary thromboembolism can occur when after treatment
7-10 days
T/F: particularly toxic drug given extravascular will lead to sloughing
TRUE
why is the 3-dose melarsomine therapy recommended
increased safety and efficacy to kill more worms
when should a repeat HW antigen test be done after treatment
9 months
describe the 2-dose melarsomine treatment
day 0 -melarsomine injection 1
exercise restriction
day 30 - melarsomine injection 2
exercise restriction
describe the 3-dose melarsomine treatment
day 0 - melarsomine injection 1
exercise restriction
day 30 - melarsomine injection 2
day 31 - melarsomine injection 3
exercise restriction
does the 2-dose or 3-dose schedules diminish the degree of insult to pulmonary vasculature and tissue
3-dose
T/F: ML preventative should be started before melarsomine tx
TRUE
how many months is a patient on ML before receiving their first dose of melarsomine
2 months
doxycycline is given for ____ prior to adulticide tx and reduces the risk of thromboembolism
28 days
what drug may be added to an adulticide tx as an alternative
prednisone (during immiticide tx)
how long should exercise be restricted during tx
1 month after 1st dose, 2 months after 2nd/3rd dose
T/F: there are no satisfactory tx for feline HWD
TRUE
how is HWD treated in cats
steroids + prophylaxis with monthly ML
T/F: heartworm prophylaxis is recommended for warm seasons
FALSE - year-round
what are oral macrocyclic lactones
- ivermectin
- milbemycin oxime
- moxidectin
what are topical macrocyclic lactones
- moxidectin
- selamectin
what breed has a high sensitivity to macrocyclic lactones
collies
T/F: slow kill programs NEED doxycycline
TRUE
