Heartworm Disease and Prevention

Shop Heartworm Prevention

Heartworm Disease: What is it?

Dirofilaria immitis lives in the heart and pulmonary arteries of an infected dog. This worm can reach up to 14 inches long. The heartworm larvae are transmitted through mosquito bites. While in the pulmonary arteries, the worm generates inflammatory response and a tendency for blood to clot inappropriately. The heart must work harder to pump blood around the worms. Worms begin mating and giving birth to baby worms called microfilariae. Microfilariae are released into the circulatory system waiting to be picked up by a mosquito to be carried to another animal. Microfilariae cannot develop into adult heartworms on their own (within the host dog in which they were born), they must be ingested by a mosquito in order to mature. Once a dog is infected, it can take 5-7 months from exposure for them to test positive.

Heartworm Disease in Cats

In cats, heartworm is a lung disease rather than a heart disease. The microfilariae develop and are transmitted the same way as they are in a dog except the feline body is an inhospitable host. Most larvae are attacked by the cat’s immune system and only about 25% will survive to adulthood. Most cats with heartworms only have a few worms and reproduction is less likely. If reproduction occurs, the microfilariae can only survive a few weeks in a cat whereas they can live up to 2 years in a dog. When the adult worm dies inside the cat, a large amount of inflammation is generated which most cats do not survive. If they do survive, there will likely be long-term damage to the lung tissue. Heartworm disease in cats can present with coughing, wheezing, difficulty breathing, or vomiting.