Every year, we are asked numerous times "If my dog was on heartworm preventive last year, why does he need to be tested this year?"  There are a number of reasons that annual heartworm testing is recommended for all dogs, even those that are on preventive year-round.  No drug is 100 percent effective, and there is always the chance (albeit a very, very small chance) that your dog could receive an ineffective dose of preventive.  More likely is the scenario of a dog going outside shortly after receiving its' monthly preventive and vomiting (it's a simple fact of life that dogs tend to vomit a lot more easily than we do!), so that the drug is not absorbed as it should be.  And even the best-intentioned pet owner will occasionally forget to give a dose, or give it a few weeks late.  Another factor can be that in growing dogs (pups that are rapidly growing or adult dogs that put on extra weight due to inactivity or health problems) your dog's recommended dose of heartworm preventive may change from month to month and underdosing will not offer full protection.

Due to the nature of heartworm infections, if your dog is tested and found to have heartworm BEFORE it is showing signs of the disease, the treatment is much more likely to be safe and effective.  If we do not test your dog, and simply start back on preventive each spring, we risk missing the early, easily-treatable stage of an infection.

We strongly recommend annual heartworm testing on every adult dog.  The only routine exceptions to annual testing are young dogs that were born in October or later of the previous year, as these dogs have not been alive long enough to have an established heartworm infection.  If you are uncertain if your young dog needs to be tested this year, please call the clinic for recommendations.