August 6, 2018

General Medical Issues

Feline Heartworm Disease

by Aili V. Heintz, DVM

Many people have heard about heartworm disease, heartworm testing, and heartworm prevention for dogs, but how come no one discusses heartworm disease in cats? Feline hearworm disease does exist, and here is what you need to know.

Can cats get heartworms?

Yes. Both dogs and cats can get heartworm disease through a bite from an infected mosquito. However, heartworm disease is much more common in dogs than it is in cats. Dogs are the natural host for heartworms, meaning that heartworms that live inside the dog can mature into adults, mate and produce offspring. This allows the number of heartworms in the dog to continue to multiply.

Cats, on the other hand, are an atypical heartworm host. Most heartworms in cats do not live to the adult stage. Of dogs and cats living in the same area, cats show only 5-20% of the risk that dogs have in contracting the disease.

How do you know if your cat has heartworm disease?

Diagnosing feline heartworm disease can be very difficult. When dogs have heartworm disease they are often carrying hundreds of adult worms. In contrast, cats may carry between one to three adult worms or may not have any heartworms that have matured all the way to adult stage.

Symptoms of feline heartworm disease are very broad and are not specific to the disease. Some signs of feline heartworm disease are coughing, rapid breathing, collapse, and difficulty breathing. An important thing to remember is that just because your cat shows some or all of these signs does not mean that it has heartworm disease. These symptoms can be seen with multiple different illnesses.

Should cats get tested for heartworm disease?

Because cats tend to carry significantly fewer worms than do dogs, there is not one specific test that we can use to identify the disease in cats. Often times, multiple blood tests, x-rays, or even a heart ultrasound or echocardiogram may be needed to definitively diagnose feline heartworm disease.

Do cats go through the same treatment that dogs do if they are heartworm positive?

No. There is currently no approved medication to treat feline heartworm disease. The drug (Immiticide) used to treat dogs can have severe side effects if used on cats. Due to the different way that cats react and respond to heartworms, we often have to treat a cat’s symptoms (such as coughing or decreased appetite) rather than the disease itself.

Again cats are not the ideal host for heartworm infection, and some infections may resolve with symptomatic care alone. This is NOT true for dogs.

Is there heartworm prevention medication for cats?

Yes. There are both oral and topical medications aimed at reducing the risk for heartworm infection in cats. If you would like to learn more about the preventative options for your cat, we would be happy to discuss what would work best for your animals and their lifestyles.


Dr. Heintz is a small and exotic animal veterinarian at Countrycare Animal Complex in Green Bay, WI. She earned her Doctor of Veterinary Medicine from University of Illinois – Urbana/Champaign. Her passion is helping all animals, whether furry, scaly, or feathered, lead long and healthy lives.