Heartgard Plus Dewormer / Heartworm / Hookworm Prevention ChewablesHeartgard Plus is a heartworm preventative that kills heartworms and helps to control and treat hookworms. Given monthly, it comes in a chewable tablet that you can feed to your pal as a tasty, beef flavored treat. Head back to the dog park, reassured that your dog is protected from nasty parasites. UsesTo prevent heartworm disease by eliminating the tissue stage of heartworm larvae (Dirofilaria immitis) for one month (30 days) after infection.