Heartgard Plus Chew, 3 Chew (3-mo. supply) + NexGard Chew for Dogs, 3 Chews (3-mos. supply)—For use in animals only. Heartgard Plus Chew for Dogs. is a heartworm preventative that kills heartworms and also helps treat and control roundworms and hookworms. It comes in a delicious once-a-month, real-beef chew that dogs love and is safe for puppies 6 weeks and older. Head back to the dog park, reassured that your dog is protected from nasty parasites with this heartworm preventative that's trusted over 2 billion times! Your furry friend must have a current heartworm test result on file with your veterinarian in order to be prescribed heartworm medication. Please visit your veterinarian to have this test performed annually to protect your four-legged friend. Proudly sourced directly from the manufacturer or their approved distributor. Guaranteed genuine and backed by the manufacturer.