If you give prevention year-round, you might wonder why we recommend yearly heartworm testing. All the manufacturers of preventative medication, as well as the FDA, recommend testing to prevent serious complications. If, for any reason, your dog contracted heartworm disease, successive doses could cause illness, or even death. Even if you're certain your dog swallowed the pill, he might go outside, eat a little grass, and throw the pill up before it was digested. That leaves him at risk of becoming infected.
Some pet owners give their dogs heartworm medication only during the hot summer months.
In Kansas, however, our changing weather leaves too much to chance. We often see mosquitoes well into October. By February, we may have a 70 degree day which is warm enough for a mosquito hatch. With weather this unpredictable, we recommend keeping your pet on medication year round. In addition, you're also protecting your pet from intestinal parasites which can be contracted from contaminated soil or other animal's feces year round.