Heartworm Flashcards
what causes heartworm?
dirofillaria immitus
what body systems does heartworm affect?
cardiovascular, respiratory, lympathic, and urogenital
how is heartworm transmitted?
mosquito bites an infected dog and ingests larvae - larvae grows through stages L1-L3 - mosquito bites another dog and deposits stage L3 larvae
prepatent period
time between infection and being able to discover parasite
6-9 months
heartworm risk factors
> 64 F all day every day for at least 1 month or >80 F every day for 10-14 days, dogs that go outside, lack of prevention, endemic regions
what are the clinical signs of heartworm?
mild (class 1): asymptomatic or occasional cough
moderate (class 2): coughing, mild exercise intolerance associated with moderate pulmonary damage
severe (class 3): cachexia, anemia, extreme exercise intolerance, syncope, possible ascites
what is caval syndrome and what are the clinical signs?
a syndrome associated with severe heartworm disease
CS: severe lethargy/weakness due to a large mass of adult worms getting lodged in the heart
what is the treatment for caval syndrome in heartworm dogs?
heartworm extraction (through jugular vein), euthanasia, Vetmedin but not often used (increases cardiac output to try to push worms back into pulmonary artery)
how can heartworm be diagnosed?
ELISA antigen test which detects proteins produced by the uterine of female worms, microfilaria testing which allows you to see the worms moving around in the buffy coat after spinning down blood, and direct blood smear which involves putting a drop of blood on a slide and looking at it under the microscope
how can you identify the different types of heartworm?
dirofilaria immitus are thicker (bigger than RBC)
acanthocheilonema reconditum are thinner
what other tests could be used to diagnose heartworm?
radiology and ultrasounds (echocardium)
echocardiums can be used to determine what class of heartworm disease the animal is in
how is heartworm treated?
restrict activity immediately after diagnosis, melarasmine deep IM injections into the expaxial muscle that contains arsenic, prednisone, and doxycycline
what are side effects of melarasmine?
pain/swelling/tenderness at injection site, fever, lethargy, anorexia, vomiting, gagging, lung congestion, depression
why are glucocorticoids used in heartworm treatment?
they are used to prevent adverse treatment reactions
used at an anti-inflammatory dose then tapered
why are doxycyclines used in heartworm treatment?
kills Wolbachia (bacteria that lives in heartworms and are released upon death of a worm)
what are the clinical signs of heartworm in cats?
coughing, dyspenia, vomiting, acute respiratory failure, neurological issues (seizures, aberrant migrants)
what is the prepatent period in cats?
5-9 months
what is HARD?
heartworm associated respiratory disease that develops in cats 3-4 months after infection
how can a cat be diagnosed with heartworm?
ELISA antibody test that is often combined with FeLV/FIV test
radiology/ultrasound: pulmonary arterial enlargement, bronchiointerstital lung pattern
how are cats with heartworm treated?
surgical extraction, inflammation therapy
what would cause a false negative in a heartworm test?
no or low amounts of female worms, tested during the prepatent period, antigen/antibody complex
what would cause a false positive in a heartworm test?
inadequate washing in well-type tests, residual antigens after treatment (wait 6 months after treatment to test)
if a heartworm test comes back positive what should be done?
confirm with another manufacturer’s test, radiographs to check extent of pulmonary and heart changes, full bloodwork to rule out concurrent disease
when should an animal start getting tests for heartworm disease?
starting at 7 months test annually
