Cat hair grows in cycles. Each follicle has a period of rapid growth (the anagen phase), followed by slower growth and then a resting phase (the catagen phase). During the resting phase, mature hair remains in the follicles and eventually detaches at the base. When the cat sheds her coat (the telogen phase), a young hair pushes out the old hair and the cycle begins anew. Cat hair grows about one-third of an inch (8 mm) each month, on average.
There are hairless cat breeds, such as the Peterbald (who is born with some hair and loses it by about age 2) and the Sphynx (whose body is covered by a fine down and who may have hair on the nose, toes, and tail). Hairlessness in these cats is due to a genetic mutation, not a health problem.
Too much female hormone in the system can slow the growth of hair. Too little thyroid hormone often impairs the growth, texture, and luster of a cat's coat. Ill health, run-down condition, hormone imbalance, vitamin deficiency, or parasites on the cat or within the cat's system may cause the coat to be too thin and brittle. If you suspect your cat's coat is below par, you should see a veterinarian. A poor haircoat often reflects a systemic health problem.
Some breeds of cats naturally have a more abundant coat. The environment also has a definite influence on the thickness and abundance of the coat. Cats living outdoors in cold weather grow a heavy coat for insulation and protection. Some additional fat in the diet is desirable at this time, because fat supplies a more concentrated source of energy for coat growth. Fat also aids in the absorption of fat-soluble vitamins, provides essential fatty acids for healthy skin and coat, and improves the palatability of food. Commercial concentrated fatty acid supplements are available. When stools become soft, the cat's diet is too high in fat.
The average indoor cat will not need any fatty supplements. As a precaution, do not add fat supplements to the diet of any cat with pancreatitis, gallstones, or malabsorption syndrome. Excess fat supplements can interfere with the metabolization of vitamin E. Before making long-term adjustments in the diet's fat content, discuss such adjustments with your veterinarian. Always consult your veterinarian before adding any supplements. You do not want to upset a well-balanced diet.
Some people believe seasonal temperature changes govern when a cat sheds. In fact, shedding is influenced more by changes in ambient light. The more exposure to natural light, the greater the shedding. This applies to both neutered and intact cats.
For cats who spend all their time outdoors, the longer hours of sunlight in late spring activate a shedding process that can last for weeks. Cats who go outdoors part of the day normally shed and grow a new coat at the beginning of summer. In fall, as the days grow shorter, the coat begins to thicken for winter. Indoor cats exposed to constant light may shed lightly and grow new coat year-round.
The tabby pattern is the most common coat pattern in the wild. The tiger is a striped tabby, the leopard is a spotted tabby, and the lion is a tabby agouti. It is also very common among domestic cats, such as this American Shorthair.
Most cats have a double coat made up of long, coarse, outer guardhairs and a soft, fine, woolly undercoat. The Devon and Cornish Rex breeds are exceptions. Rex cats have a single coat made of fine curly hair. The Selkirk Rex has a slightly longer, curly coat. These cats shed but less than a cat with a normal coat. This is a dominant mutation.
Wirehaired cats have a tightly crimped coat, including the whiskers. This is a dominant mutation. The coat is coarse and harsh to the touch.
When a cat with a double coat begins to shed, the undercoat is shed in a mosaic or patchy fashion, giving the cat a moth-eaten look. This is perfectly normal. Totally indoor cats may shed somewhat all year round and never go through this kind of extreme shed. When shedding begins, prevent skin irritation by removing as much dead hair as possible by daily brushing.
This article is excerpted from “Cat Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.
Copyright © 2008 by Delbert Carlson, DVM, and James M. Giffin, MD. All rights reserved.
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