ITHACA, N.Y. -- Seriously overweight cats are more likely to suffer diabetes mellitus, lameness and non-allergic skin conditions, a Cornell University veterinarian's four-year follow-up to a feline obesity study has shown.

Most likely to be tubby are neutered, apartment-dwelling, mixed breed cats eating prescription cat food.

"The original obesity study and the follow-up confirm what veterinarians and cat owners have suspected for a long time," said Janet M. Scarlett, D.V.M., associate professor of epidemiology in Cornell's College of Veterinary Medicine. "Too much extra weight is not healthy for the cats, but being very thin can be a problem, too."

Scarlett was a collaborator, along with veterinary nutritionist Susan Donoghue, in the landmark 1989 study of 2,000 cats at 31 veterinary clinics in the Northeast, as well as the principal investigator of the tracking study. The Waltham Centre for Pet Nutrition in the United Kingdom funded the first study, which found that about 25 percent of cats brought to veterinarians are overweight: 20 percent were ranked as "heavy" by veterinarians and 5 percent were considered "obese." Slightly more pet owners -- about 29 percent -- thought their cats were overweight in the same survey.

Ralston Purina Co., the American pet food manufacturer, funded the four-year follow-up, in which Cornell veterinary students called as many of the original pet owners as they could locate and asked about the cats' health. Researchers also reviewed veterinarians' medical records for the animals in the first survey. Among the findings:

• Overweight cats, including those considered "heavy" and "obese," are four-and-a-half times more likely to develop diabetes mellitus, compared to optimal weight cats.

• Obese cats are seven times more likely to require veterinary care for lameness, caused by joint diseases such as arthritis or muscle injuries, compared to optimal weight cats. Heavy cats
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