The 7 Deadly Truths About Heartworm Disease in Cats

As the weather gets colder and people and pets spend more time indoors, many families stop their pets’ heartworm prevention. "It is too cold for mosquitoes," "My pet does not go outside," and "We don't have mosquitoes where I live" are all common reasons people stop giving their pet heartworm prevention in the winter. Unfortunately, pets are susceptible to heartworms and intestinal parasites in the winter. 

Watch this video and learn why it is so important to protect your cat from heartworms year-round.

Important points:

Heartworms are mostly associated with dogs but sadly, cats can get heartworm disease too.  Heartworms are 9-11 inch worms that live in your cat’s heart and in the arteries leading to the lungs. Heartworms are transmitted when an infected mosquito bites a cat and deposits baby heartworms (larvae) into the bloodstream. The larvae migrate and mature over several months and end up in the right side of the heart. It takes about 6 months to mature into adult worms. Recent studies of cats with heart and respiratory disease have found that the incidence of heartworms is greater than previously thought. Just a small number of worms or even immature worms can cause heartworm-associated illness in cats, making it difficult to detect an infection.

Adult heartworms cannot be treated in cats, as the dying worms can cause a severe reaction and even death. If a cat is diagnosed with heartworms, the only option is to manage the symptoms heartworm disease causes, prevent further heartworm infection, and wait for the cat’s immune system to slowly kill the heartworms and for the body to repair itself. There can be very serious health consequences, even death, during the months to years this takes.

Indoor cats get heartworms too!  About 25% of the cats who have heartworm disease are reported to be indoor cats.  The mosquitoes that come into the house are just as dangerous as the ones outside.

How can you protect your cat? 

We recommend that every cat have Revolution topical drops applied monthly (to the back of the neck) to treat or control hookworms, roundworms, fleas, heartworms and ear mites. No other product provides this kind of comprehensive parasite protection. Revolution for cats is available at Animal Hospital of North Asheville. Please call and request a prescription.

Learn more about protecting your cat from heartworm disease by clicking on one of our past articles: 

Heartworm in Cats

Heartworm Fact Sheet

Or visit the American Heartworm Society website ( to learn more about heartworms in cats and dogs.