Tricia Kieffer, Emily Ellis, & Uwe Pott
Human
Biology
How much heartworm prophylaxis is enough?
Canine heartworm disease, which is caused by the nematode Dirofilaria immitis, is a
dangerous, and if left untreated sometimes lethal condition in dogs. Dogs become infected with heartworm when they
are bitten by mosquitoes that carry the infectious larval stage (L3) of the
worm. In the dog, these larvae develop
into the adult worms, which migrate through the body and eventually reside in
the heart and associated blood vessels.
The worms produce microfilaria which can be taken up by mosquitoes
during another blood meal. Development
of the L1 larvae into the L3 stage in the insects at appropriate temperatures
closes the life cycle of the parasite.
The development
of heartworm disease in dogs can be prevented by chemoprophylaxis with ivermectin (Heartgard®)
or related substances. These substances
kill the larvae before they can develop into adult worms. Many veterinarians recommend year-round
prophylaxis with a monthly dose of ivermectin or,
alternatively, treatment from April through December in colder climates as
found in the state of
Our goal in this study is to
re-evaluate the heartworm infection risk for dogs in the