Your dog should be on heartworm prevention year round. Heartgard also helps prevent the most common intestinal parasites. Purchase 12 months of Heartgard Chewables for you canine friend and receive a $12 rebate. You will also be entered into the drawing for a 32" Samsung LED television to be given away in May. This offer is sponsored by Merial, the manufacturer of Heartgard Chewables.