3 Common Types of Pet Heartworm Meds

Updated Sep. 7, 2022

Where to Start?

The American Heartworm Society recommends that animals living in all parts of the U.S. be given heartworm preventive medications on a year-round basis. But which are the best heartworm meds for dogs and cats? While there isn't necessarily a "best heartworm medication" there are certain types of meds that may be more convenient for you and effective for your pet (if given in the proper dose on a regular schedule). Here are three of most common types of heartworm preventive medications to discuss with your veterinarian.

Adapted from an article by Jennifer Kvamme, DVM

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1. Oral Monthly Heartworm Medications

The heartworm preventives you are probably most familiar with are the once-a-month tablets or chewables. Many of the various oral heartworm medications available today contain either ivermectin or milbemycin as the active ingredient and many serve more than one function— not only killing heartworm larvae but also eliminating internal parasites such as roundworms and hookworms. You do, however, need to watch your dog or cat to be sure he/she chews the entire piece or tablet and doesn’t spit any of it out. Otherwise, the heartworm medication loses its effectiveness.

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2. Topical (Spot-on) Heartworm Medications

These heartworm medications are applied monthly to the back of the dog or cat’s neck, or between the shoulder blades on the skin. Not only do these preventives protect against heartworms but there are some with active ingredients that work to eliminate such things as fleas, ticks, mange mites, and roundworms. These heartworm preventives are toxic if ingested, so be sure to isolate your pet for a time after application — both to prevent your pet from coming in contact with children or other animals and to prevent them from rubbing the medication off on furniture, carpet, etc.

3. Injectable Heartworm Medication

Along with being used in other forms of heartworm preventives, Moxidectin can be administered as an injection for up to six months protection from heartworms. The injectable heartworm medication does come with restrictions on its use. Veterinarians must administer this heartworm medication to their patients, and this is only after intensive training in its proper use. Your veterinarian is also required to record the lot number of the product used for your pet and must report any adverse effects that may arise.

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Follow Instructions and Consult Your Vet

No matter which medication you choose for your dog or cat, read the medication's label closely and follow its instructions. Additionally, tell your veterinarian if your pet shows signs of illness after administration and be sure to have your dog or cat tested yearly for heartworms.