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Auburn University

November 6, 2007

AU veterinary professors release landmark study on feline heartworm disease

A landmark study led by two Auburn University veterinary professors has proven that immature heartworms cause long-lasting lung disease in cats, a finding that dispels the notion that heartworms only affect dogs. “This redefines the disease in cats and it emphasizes the need for prevention,” said Ray Dillon, the Jack O. Rash Chair of Medicine in AU’s College of Veterinary Medicine. “The previous thought was that only adult heartworms were significant, but that is clearly not the case.”

The culprits are immature heartworms that grow only to 1 to 2 1/2 inches long and cause Heartworm Associated Respiratory Disease. Heartworm infection takes place when a mosquito carrying infective, microscopic-size heartworm larvae, bites into a cat or dog. In cats, many heartworms die three to four months after infection and disintegrate in the lungs, leaving the disease and creating lung tissue damage. This occurs even if the cat never gets an adult heartworm, and he says it is a clinical disease that starts three months after the mosquito bite, not the six-month time usually associated with adult heartworms in dogs.

“Previous studies focused on the heart for cats, but we now know that research should have looked more at the lungs for answers,” said Byron Blagburn, a parasitologist and AU Distinguished University Professor. “This was due to thinking that the heartworms would affect cats just like dogs. They are more likely to infect dogs’ hearts, but cats’ lungs.”

Heartworm prevention for dogs has been stressed for years, says Dillon, because heartworms in dogs can live three to five years in the heart and grow to 16 inches long. “The damage is obvious in dogs, but immature heartworms in cats are like juvenile delinquents and hit-and-run drivers,” Dillon said. “They come in and create lung disease and leave no evidence directly related to heartworms.” MORE

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Dr. Byron Blagburn's Web site
Dr. Ray Dillon's Web site