Heartworm Disease in Cats

Heartworm affects cats too.  Largely thought of as a dog parasite, heartworm occurs in cats as well.  Moreover, 1 in 4 cats diagnosed with heartworm infection live indoors.

Heartworm is a worm that lives in the right side of the heart or pulmonary arteries in many species, including dogs, cats, ferrets, coyote, fox, wolves, and sea lions.  Some of the wild carriers of this parasite live and thrive in this region.

Cats are not a typical host of heartworm, therefore heartworm infection behaves differently in the cat.  While a dog could have more than 30 worms, a cat will generally have less than 3. Heartworms often do not mature to adults in cats, and because current tests evaluate for adult worms, infections in cats can go undiagnosed.  The early signs of heartworm infection in cats include coughing, asthma-like signs, vomiting, and poor appetite.  Over time, the worms die and send fragments to the lungs.  More serious signs such as collapse or sudden death can occur due to lung injury. 

The treatment that is used to effectively eliminate adult heartworm infections in dogs is not safe to use in our feline friends, underscoring the need for prevention.  Monthly preventatives are effective and highly recommended for cats.  An added benefit is that some also protect against fleas and intestinal parasites.  If infected, medications can be given to manage the signs that heartworm causes, but the cat is faced with the task of naturally clearing the parasite over time—usually 2 to 3 years.    

Our understanding of this parasite continues to evolve.  Cats, in their unique style, react to this infection in their own way.  We would expect nothing less of them. 

The American Heartworm Society Website has great information about heartworm in dogs and cats and was the source for the information contained in this article. 

https://www.heartwormsociety.org

article written by:

Laura Rau-Holl, DVM

Wolf Merrick Animal Hospital, Kenosha, WI