With the exception of a few hairless breeds, all dogs and cats have a smooth, even coat, no matter what their age. If your pet is developing bare spots or has a patchy, moth-eaten look, there is almost certainly something wrong -- anything from parasites to infections, nutritional deficiencies to hormonal problems.
It is almost impossible to tell at home what is causing fur to fall out, but you can get a few clues from the appearance of the coat, says Karen L. Campbell, D.V.M., associate professor of dermatology and small animal internal medicine at the University of Illinois College of Veterinary Medicine at Urbana-Champaign.
Pets with circular patches of red or crusty skin, for example, often have ringworm, a type of fungus that is readily passed from pet to pet. Ringworm occurs throughout the country, but it is most common in places with hot, steamy weather. Cats are more likely than dogs to get ringworm, says Dr. Campbell. In addition, some cats may be asymptomatic carriers, meaning that they can spread the fungus without having symptoms themselves.
Fur loss in dogs is sometimes caused by demodex mites. These are tiny parasites that normally live peacefully in the hair follicles of dogs. But sometimes the mites multiply -- and when they do, they can cause substantial hair loss, explains Dr. Campbell. The hair loss starts around the eyelids, mouth, and front legs, causing bare patches about an inch around. Eventually, the patches may enlarge, causing very large bare patches that often get infected.
When your pet is scratching hard enough to make the fur fly, you should always suspect fleas. Another itchy condition is seborrhea, in which oil glands in the skin get overactive, causing greasy, foul-smelling fur and bare patches that may resemble those caused by ringworm.
A thinning coat can be caused by a hormone imbalance. Too little thyroid hormone, for example, will cause hair to fall out all over your pet's body, and the hair that remains will be brittle and coarse. Too much estrogen can have the same effect, says Donna Angarano, D.V.M., professor of small animal surgery and medicine at Auburn University College of Veterinary Medicine in Auburn, Alabama.
"Nutritional deficiencies are rare these days, but they do occur and can cause hair loss or a dull, thin hair coat," says Craig N. Carter, D.V.M., Ph.D., head of epidemiology at Texas Veterinary Medical Diagnostic Laboratory at Texas A&M University in College Station. Pets that don't get enough protein or essential fatty acids may develop a dry, thin coat, he explains. "Nutritional deficiencies generally happen when people don't feed their pets commercial pet foods, most of which are formulated to meet your pet's nutritional needs, and instead rely on table scraps," he says. And if you are feeding your pet a generic food, you might want to upgrade her to a brand-name chow.
In addition, some Arctic breeds like Siberian huskies and Alaskan malamutes have a genetic tendency to absorb too little zinc. This can cause hair loss along with scaly, crusty patches on the skin.
See Your Vet If...
- The skin has circular patches that are red and crusty
- Your pet is always itchy
- Her fur is brittle and coarse
- Your pet is shedding or scratching more than usual
- He has scales, bald patches, or a rash
- He has severe dandruff or dry skin
- His fur is greasy or smelly even after baths
- Your pet has broken out in hives and is having trouble breathing
- He has a bad sunburn
- There has been a significant change in skin color, or the skin seems loose
- There is a lump or swelling beneath his skin
- Your pet has a sore on the skin that won't heal
- The skin of the lips, abdomen, or rectal area is yellow
- There are red or purple dots or splotches on his skin
Back to the Symptom Solver Main Page
Copyright 1999 Rodale Press, Inc. All rights reserved.