Your dog should be tested for heartworms annually. We can take care of this during your pets annual wellness visit. If you administer heartworm prevention to your pet every thirty days the chance of your pet developing a heartworm infection is low, however, nothing is perfect. At times you may miss a dose or fail to give it in thirty days. Your dog may vomit or spit out their dose and “lose” their preventative. The danger in not testing is not knowing. It is our job as your pets veterinarian to detect problems before they become a serious illnesses. If your pet did contract heartworms it is important to detect it and treat it as soon as possible.