Canine heartworm, Dirofilaria immitis, is a parasite that requires both the mosquito and dog to complete its life-cycle. Below is a simple illustration of the typical life cycle of the heartworm.

Prevention of heartworm disease includes initial testing to ensure a negative result, then monthly preventative medication given that will kill any larvae your pet may become infected with before it can mature and migrate to the heart. Heartworm testing is extremely important before starting prevention as, once infected, treatment is necessary and preventative measures are no longer an option.

Fortunately, most patients are negative for heartworm, and we can begin the preventative medication. We typically prescribe one of the monthly medications and recommend treatment from June through November. Even though you may see mosquitoes before and after the treatment period, they are not infective at that point as the heartworm larvae require a period of warm weather before they can live out of the mosquito.

Here at Valley Veterinary Hospital, PC, we follow the recommendations of the American Heartworm Society for testing. Previously, the recommendations in low-endemic areas like Colorado were to test and prescribe preventative medication, and, if compliance is good, to retest every other year. Now it is recommended to test yearly. This recommendation is based on the increasing incidence of disease found in low-endemic areas. Remember, although the preventative medications are usually quite effective, they are not 100%. Please, don't let your furry companion be a statistic.

Learn more from the American Heartworm Society's website.