Why does my dog need a heartworm test every year?

My dog is on heartworm prevention year-round, so why does my dog need a heartworm test every year?

Heartworm is a parasite that is transmitted via mosquito bite. It can cause lung damage and liver failure if undetected. A regimen of heartworm pills is important to prevent the parasitic larvae from hatching and traveling through your dog’s system. With any medication, there is a chance that your dog will spit it out at some point. A quick, simple test at our office will ensure that heartworm is detected early in your dog’s system and can be treated before it causes any serious illnesses.