The Facts About Feline Heartworm Disease

The Facts About Feline Heartworm Disease

Revalence and Role of HARD

FHWD is more widespread and common than previously thought. For many decades it was assumed that cats were resistant to infection, but we now know that this is an inaccurate view of heartworm infection (HWI) in this species.

Cats are more resistant to heartworm than dogs, but they are considered a susceptible host. While the rate of adult HWI in cats is only 5% to 20% of that in dogs,1 these numbers fail to consider the important physical effects caused by immature heartworms that die before they fully mature, and the number of cats whose infections go undiagnosed.

In cats, immature heartworms reaching the pulmonary vessels often die, and in doing so, trigger an intense inflammatory reaction that causes vascular, interstitial, and alveolar disease—a syndrome now termed heartworm-associated respiratory disease (HARD).

When adult HWIs are combined with the far more prevalent HARD, the true incidence of heartworm disease in cats is vastly greater than previously believed. Whether damage is caused by 9-inch adult heartworms or immature adults, it is still considered “heartworm disease” as far as the cat’s lungs are concerned. Both adult infection and HARD are clinically significant, causing significant disease and even death (in patients infected with adult heartworms) in the cat.
​

Read More