Heartworm prevention is very important, and we want your pet to be covered every month, however it is a common policy for your pet to have to have a test every year. That is because the manufacturers of the heartworm prevention will guarantee their product, meaning that if you have proof of purchase and a yearly test and your pet happens to get heartworm disease the manufacturers will pay for the treatment. #chateudogandcat #veterinarian #vettechtok #fyp #heartworm