Heartworm is a difficult-to-treat and potentially fatal disease in dogs and cats, but it can be prevented with drugs approved by the Food and Drug Administration (FDA).
A dog or cat can get heartworm disease through a mosquito bite. There are more than 60 different species of mosquitoes that can transmit heartworms. If the mosquito is carrying the heartworm larvae (infective stage) when it bites a pet, the disease is likely to be transmitted to the pet. The larvae enter the bite wound and move through the pet’s body. The adult worms live in the heart, lungs, and nearby blood vessels, where they can grow up to 12 inches long.
Dogs, cats, and some other mammals can get heartworms only if bitten by an infected mosquito; the disease is not contagious from one animal to another. Most dogs and cats with heartworm infection do not show any symptoms until the disease becomes severe. At that stage, symptoms may include
- difficulty breathing
- reduced appetite and weight loss
- vomiting and gagging (usually only in cats)
- lung, liver, kidney, or heart failure, leading to death