Feline heartworm disease has been diagnosed in all 50 states. Wherever dogs are considered to be at risk for heartworms, cats are at risk as well.
 

Research has shown that signs such as coughing and difficulty breathing, which are often diagnosed as feline asthma or allergic bronchitis, can be caused by the presence of heartworms in either larval or adult stages. Heartworm associated respiratory disease, or HARD, is the term for this condition.

Heartworm infection occurs when a mosquito carrying microscopic heartworm larvae takes a blood meal from a cat. The larvae enter through the bite wound and develop in the cat’s tissues. The immature worms then enter a blood vessel and are carried to the arteries in the lung where they cause an inflammatory reaction. Most worms die at this stage, causing even more inflammation. The worms that progress to the adult stage can live undetected for a couple of years, but when the adult worms die the inflammation can be severe enough to cause death.

 
Symptoms Associated with HARD:

ONLINE RESOURCES

KNOW Heartworms is an awareness campaign cosponsored by the American Association of Feline Practitioners (AAFP) and the American Heartworm Society and funded by an educational grant from Pfizer Animal Health. The campaign was created to raise awareness of feline heartworm disease and HARD. The website focuses on the "Five Myths and Misunderstandings" of feline heartworm disease. 

The American Heartworm Society has the most comprehensive and up-to-date information about heartworm disease, including guidelines for diagnosing, treating, and preventing heartworms in cats, a feline heartworm animation, a glossary of heartworm-related terms, and a "Just for Kids" page. 

Ray Dillon, DVM, MS, DACVIM, of Auburn University has created a website to share his cutting-edge research on feline heartworm disease. His research is raising awareness among cat owners and veterinarians.