Why does my dog need a heartworm test if he is on heartworm prevention year round?

All dogs should be tested for heartworms every 12 months during his or her annual visit for routine preventive care. Nothing is perfect. People miss doses of medication or fail to give it the same day each and every month. Pets vomit frequently and at times “lose” their dose of prevention. At times they spit it out. Heartworm preventives are “nearly” perfect, but nothing is perfect and the danger of not testing is in not knowing. If you administer heartworm prevention to your pet as scheduled, the chance of your pet developing an infection is extremely low. Our job as your veterinarian is to ensure your pet’s good health by detecting problems before they progress into serious issues. Heartworm disease is a serious issue and when present, should be detected and treated as soon as possible. Testing annually is important.