Heartworm Disease Part II Flashcards
what is the primary screening test for heartworm in dogs?
antigen tests
what is the primary screening test for heartworm in cats?
antibody tests
what does heartworm antigen testing test?
protein released from adult female reproductive tract
why should cats be tested for both heartworm antigen and antibody?
much less sensitive due to low worm burdens
what does a positive heartworm antibody test indicate?
exposure, not active infection necessarily
how can you confirm diagnosis of heartworm in a cat after a positive antibody test?
antigen testing and/or echo
what is the most sensitive microfilaria test?
modified Knott’s test or some other concentration test
should you test dogs for microfilaria that are heartworm positive by antigen test?
yes- always
how many cats with heartworm disease are amicrofilaremic?
more than 2/3
if an animal is microfilaremic, what should you check?
confirm species as Dirofilaria immitis
rule out Acanthocheilonema reconditum
what is the primary manifestation of heartworm disease on radiographs?
pulmonary disease
what is the dose of ivermectin for heartworm?
6-12 microgram/kg
what stages of larvae to macrolides kill?
L3 and L4
which dogs should be on heartworm preventative?
every dog over 8 weeks of age
what should felines be on to prevent heartworm disease?
macrolide preventative
what are the goals of heartworm treatment?
kill Wolbachia
eliminate microfilaria
kill adult worms
minimize pulmonary parenchymal and arterial pathology
treat right CHF and significant PHTN if present
why do we pre-treat for 1-2 months with doxycycline and a macrolide before giving melarsomine dihydrochloride?
melarsomine dihydrochloride only toxic to L5 and adults
can melarsomine dihydrochloride be given to cats?
no
when does peak worm death occur?
1-3 weeks post treatment of melarsomine dihydrochloride
what are the ancillary therapies for heartworm?
exercise restriction
doxycycline
ivermectin
corticosteroids
what can be found of physical exam with heartworm with the heart?
no abnormalities
weight loss and cachexia
loud and/or split S2
murmur of tricuspid valve regurgitation +/- right-sided thrill
S3 gallop
jugular venous distension, hepatosplenomegaly, abdominal effusion
who cannot be antigen positive?
puppies <6 months old
why is detection of microfilaria an insensitive method of diagnosis for heartworm?
prevalence of occult infection
what are the causes of occult infection?
iatrogenic
immune-mediated
unisex infection
prepatent infection
what is echo used to evaluate for in dogs with heartworm disease?
severity of pulmonary hypertension
caval syndrome
cor pulmonale
parasite burden
concurrent heart disease
why is extra-label use of ivermectin at 50 microgram/kg not recommended?
anaphylactic shock: rapidly microfilaricidal
can melarsomine dihydrochloride be given to dogs with caval syndrome?
no
can you give melarsomine dihydrochloride to cats?
no
what are the possible side effects of melarsomine dihydrochloride?
local pain/inflammation
GI signs
neurologic complications
pulmonary edema
renal and hepatic toxicity
pulmonary thromboembolism
death
what are the ancillary therapies for heartworm in dogs?
exercise restriction
doxycycline
ivermectin
corticosteroids
heparin/antiplatelet agents
oxygen, phosphodiesterase inhibitors
RCHF therapy
