Guest Blog: Feline Heartworm Disease

By: Scott Gellman, VMD
1. My Indoor Cat Can’t Get Heartworms.
Heartworm disease has been found in all 50 states, in all climates, and in mosquitoes both inside and outside homes. All cat owners should be mindful of the fact that it only takes one mosquito to infect a cat, and the only way to reduce the risk of your cat becoming infected is to keep them on monthly heartworm preventive medication.
2. Heartworm Disease Is a Dog’s Disease.
The good news is cats do not suffer from heartworms as often as dogs do; however the disease they cause is equally serious. Unlike dogs, cats do not serve as a natural host. In fact, many worms in cats are produced in a smaller number and often die before reaching adulthood. A typical heartworm infection involves up to six worms, primarily juveniles. Despite smaller numbers, cats are still susceptible to serious pulmonary and cardiac damage while fighting, the often undiagnosed infection.
3. It’s a Heart Disease.
The name “heartworm disease” is a misnomer, as the disease mostly affects the lungs and not just the heart. Signs are often mistaken for feline asthma, allergic bronchitis or other respiratory diseases.
So what are the signs of heartworm disease in cats? The most common signs of feline heartworm disease are coughing, lethargy, and difficulty breathing. Periodic vomiting or anorexia may also be indicators of heartworm disease; and in more serious cases, weakness, collapse, seizures, or even sudden death.
4. Only Adult Heartworms Cause Problems.
Cats do not need an adult heartworm to start showing signs; in fact, larvae are a main cause of the problems. Studies show 50 percent of cats infected with heartworm larvae have significant disease of the small arteries supplying blood to the lungs. Since most worms in cats die before reaching adulthood, many infections are often missed. However, for those adult heartworms that do not die, they can live as long as 2-3 years in a cat, causing irreversible damage to the heart.
5. If My Cat Has Heartworms, I’ll know immediately.
Signs of heartworm disease can be difficult to detect in dogs or cats, especially in the early stages. In cats, signs of heartworm disease can be subtle and misleading because they’re similar to signs of many other feline diseases.
Application of a monthly preventative, such as Revolution, year-round is extremely important in preventing your cat falling prey to this devastating disease. It is equally important to stay up-to-date, as missing even a couple of months of preventative may give the worms the chance to reach adulthood.
Dr. Scott Gellman is a veterinarian at our sister hospital, The Chestnut Hill Cat Clinic, in Philadelphia, Pennsylvania. Learn more at