One mosquito bite can infect a cat with heartworm, a potentially destructive and insidious disease, which reveals itself as H.A.R.D. (Heartworm Associated Respiratory Disease). The American Heartworm Society (AHS) and the American Association of Feline Practitioners (AAFP) have teamed up to get this urgent message out to cat owners through the KNOW Heartworms campaign (www.knowheartworms.org). Experts now feel that heartworm prevention in cats is extremely important because the dangers of heartworm disease are much more significant that previously believed. Here are five common myths about heartworm disease that can put your pet at serious risk. Dogs vs. Cats. Heartworm is not just a canine disease, and it affects cats differently than dogs. Indoor Cats vs. Outdoor Cats. Heartworm disease is mosquito-borne and evidence has shown that indoor cats are just as susceptible to it as outdoor animals. In a North Carolina study, 28 percent of the cats diagnosed with heartworm were indoors-only pets. Its a Heart Disease. Actually, “heartworm disease” is a misnomer. It mostly affects the lungs, not just the heart. The disease is frequently mistaken for asthma and other respiratory disorders. Adult Heartworms vs. Larvae. New research shows that heartworm larvae at all stages – not just adult worms – can cause serious health problems. Diagnosis.