Valley Veterinary Hospital, PC

1191 Ken Pratt Boulevard
Longmont, CO 80501


Valley Veterinary Hospital P.C.



 Canine heartworm, Dirofilaria immitis, is a parasite that requires both the mosquito and dog to complete it's life-cycle.  Below is a simple illustration of the typical life-cycle of the heartworm. You can also click on the American Heartworm Society banner at the bottom of this page to watch a short educational video. 

 Heartworm Society Banner


Prevention of heartworm disease includes initial testing to ensure a negative result then monthly preventative medication given that will kill any larva your pet may become infected with before it can mature and migrate to the heart. Heartworm testing is extremely important prior to 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 June through November.  Even though you may see mosquitos before and after the treatment period they are not infective at that point as the heartworm larva 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.


 Please click on the American Heartworm Society banner for more detailed information and please feel free to contact us with any questions.

Heartworm Society Logo

Longmont, CO. 80501-80503