Tip on Preventing Heartworm Disease in Cats

Cats can get heartworm disease. Feline heartworm disease is a serious parasitic disease caused by a long, thin worm, Dirofilaria immitis, that lives in the blood vessels and heart of infected cats.

The disease is spread from dog to cat by mosquitoes. The mosquito bites a dog with heartworm infection, collects some of the microscopic heartworm offspring, and then after a couple of weeks, passes these on to another dog or to a cat. Inside the cat, the microscopic heartworm can grow into a parasite exceeding a foot in length. The life cycle is somewhat complicated. The important thing is to prevent worm development using safe and effective preventative drugs.

Heartworms are present (endemic) in most parts of the United States and in many parts of North America. Mosquitoes are the key – without them the disease cannot spread. The highest rate of infections is found in subtropical climates like those of the southeastern United States, the Gulf States and Hawaii.


Owners of all cats living in areas endemic to heartworms should discuss the pros and cons of preventative care with their veterinarian.

If dogs in the area receive heartworm prevention, it is likely that cats also may benefit from this protection. Heartgard for cats® and Revolution for cats® are both safe and effective products for cats only. Do NOT use your canine heartworm medicine in your cat! The drug dosing is very different between species.

Speak to your veterinarian about the need for preventative therapy, administration guidelines and when to start and stop prevention treatments. Some recommend that before beginning heartworm prevention, any cat over 7 months of age should first have a heartworm blood test.