Heartworm medications target the parasitic worm Dirofilaria immitis, or heartworm. When infection occurs, these worms travel through your dog’s bloodstream and into the heart and lungs. Monthly heartworm medications work by killing heartworm larvae before they develop into adults. In addition to heartworms, many of these products kill other parasitic worms such as roundworms, hookworms and whipworms, as well as other insects and parasites such as fleas, ticks and mites. Speak to your vet to ensure your pet's medicine meets his specific needs.
Oral heartworm medications, such as milbemycin oxime and ivermectin with pyrantel pamoate, come in chewable tablets that you give your dog monthly. In addition to heartworms, ivermectin with pyrantel pamoate kills intestinal roundworms and hookworms. Milbemycin oxime kills heartworms, roundworms, hookworms and whipworms.
Topical medications, such as selamectin or moxidectin and imidacloprid, apply directly to your dog’s coat at the back of the neck, between the shoulder blades. In addition to heartworms, selamectin also targets fleas, ticks, scabies and ear mites. A formulation of moxidectin and imidacloprid treats heartworm, as well as intestinal roundworms, hookworms, whipworms and fleas.