Lifecycle:
A female mosquito lands on an animal and takes a blood meal, during this meal she releases the heartworm offspring, Microfilaria, into a pets blood stream. The Microfilaria will cycle through the blood stream for 6-8 months and once full grown, will settle in the heart. These adult Heartworms then mate and release their offspring into the bloodstream where a then uninfected mosquito goes to take a blood meal and the cycle starts all over again.

Testing:
Heartworm tests, while an amazing tool in the veterinary field, also has some limitations. Heartworm tests are only able to detect the adult female antigen, so if the infection is new, or it is an all male infection, the antigen test will give a negative reading. We are also able to look at a blood sample and look for Microfilaria, but this way of testing requires a large number of larvae, so if the infection is small this may not provide true results.

Treatment:
Treatment for Heartworm disease is expensive and complex, so veterinaians may want to do multiple tests before persuing treatment. If you decide to go ahead with treatment, it typically consists of restricted activity, multiple injections within the back muscles, oral medications and in some cases, overnight hospitalization.

Prevention:
While in Minnesota we may not have mosquitos year round like the southern states, but it is still recommended to give year round prevention to our pets since the lifecycle is so long.  Heartworm prevention also has a general dewormer in for intestinal parasites which pets can aquire year round.  Prevention is sigificantly cheaper than treatment, you cant buy approimately 7 years of heartworm prevention for the cost of the average treatment.

For more information, visit the American Heartworm Society website.