Heartworm Treatment for Cats


Heartworm is a parasitic infestation transmitted to dogs and more rarely, cats, by bites from infected mosquitoes. Heartworm is a potentially fatal health threat and often requires aggressive, prolonged and painful treatment.

Prevention is Easier Than Treatment

Heartworm disease is easier to prevent than it is to treat. The first line of defense in preventing your pet from any disease or infection is through the promotion of a healthy immune support by providing optimal nutrition, exercise and play, minimizing stress, thoughtful vaccination protocols, and veterinary care.

According to the Integrated Pest Management Information Network from North Carolina State University, “Healthy animals are best able to withstand and, to some extent, avoid infestation.” Dr. Michelle Tilghman, D.V.M. says, “Strengthen [your pet’s] resistance with whole foods. Dogs and cats are more likely to resist heartworms when they are given all-natural foods, which help keep the immune system strong.”

The next line of defense should be reducing breeding environments for mosquitoes in areas where your pet spends a lot of time. Standing water sources are needed for mosquitoes to breed, so whenever possible it is best to eliminate these breeding grounds, which should reduce mosquito bites to both humans and pets. Products like Garlic Barrier will also help reduce the number of mosquitoes and other unwanted insects in your yard.

The FDA recommends the following preventative measures for ensuring your pet does not succumb to heartworm, which may include tablets, injectables, and topical treatments (these preventatives will require a prescription from your veterinarian):

  • Oral pill or tablet: ivermectin, milbemycin oxime
  • Spot on topical treatments: selamectin, moxidectin
  • Injectable (for dogs only): moxidectin

In addition to these prescribed allopathic preventatives, there are a number of holistic products intended to prevent heartworm infection. Many of these are topical sprays featuring blends of various essential oils. Be very careful using these sprays if there are cats in your home, as they can be toxic to resident kitties. Additionally, there are a wide variety of herbs that are recommended (either topically or internally) for the prevention of mosquito bites and thus heartworm (examples include garlic, black walnut, and mugwort). Some pet owners report great success with using a spray of organic apple cider vinegar.

Talk to your veterinarian about the heartworm preventatives which would be best for your pet. Depending on where you live, you may need to provide heartworm preventatives year round or only in the warmer months when mosquitoes thrive. Ask your veterinarian about seasonal risks and infection rates in your geographic region.

Heartworm Treatment

At this time in the United States there is no approved heartworm medicine for treating the disease in cats. It appears as though heartworms go away without treatment in some cats. For the unlucky cats whose heartworms do not “just go away”, frequent monitoring is a must, prednisone is sometimes advised, and in severe cases, surgery may be an option to remove significant worm loads.

Heartworm medications generally involve a two-step approach to addressing the parasite load. There will be medication for killing the adult worms (known as adulticide treatment) as well as medications for eliminating the microfilariae (offspring). The microfilaricide is composed of the same active ingredients in many recommended preventatives. The adulticide is actually a arsenic compound injection administered by your veterinarian.

Hospitalization will likely be required for some stages of treatment. Additionally, your veterinarian will likely recommend fairly limited physical exercise and possibly even crate rest for all or some of the treatment stages.

For more information on keeping your pets safe from heartworms, check out the American Heartworm Society at www.heartwormsociety.org. They have great resources about heartworm disease in both dogs and cats, along with maps showing prevalence of heartworm incidence by geographic region in the United States (check the risk in your area here).

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