Diseases with Hair Loss in Cats

This lists a group of skin conditions that affect the appearance of the coat and hair. These diseases do not cause your cat much discomfort -- at least not at first. Hair loss is the main sign. It may appear as impaired growth of new hair, or you may notice a patchy loss of hair from specific areas of the body. At times, the coat does not look or feel right and may be greasy or coarse and brittle. Many of these conditions are related to hormone production.

Congenital hypotrichosis: A genetic condition where kittens lose any hair they are born with by about 4 months of age.
Cortisone excess: Symmetrical hair loss over trunk and body, with darkening of the underlying skin. Seen with Cushing’s disease. May also indicate a thyroid problem. Thinning of the skin is also seen with this condition.
Demodectic mange: Thinning and loss of hair around the eyes and eyelids, giving the cat a moth-eaten appearance. Not common in cats.
Eosinophilic granuloma: Raised, red circular plaque on the abdomen or insides of the thighs (eosinophilic plaque); or linear plaques on the backs of the hind legs.
Feline endocrine alopecia: Thinning or balding of the coat on insides of the back legs, lower abdomen, and genital area. Distribution is symmetrical. Occurs most often in neutered males and spayed females.
Hyperthyroidism (excess thyroid hormone): About one-third of cats with this endocrine problem will have hair that pulls out easily and hair loss.
Hypothyroidism (deficient thyroid hormone): Dry skin and thinning of the haircoat. Hair becomes dull and brittle. Rare in cats.
Indolent (rodent) ulcer: Red shiny patches of hairless skin. Usually involves the middle of the upper lip and occasionally the lower lip. Not painful.
Psychogenic alopecia: Thinning of hair in a stripe down the back or on the abdomen. Caused by compulsive self-grooming.
Ringworm: A fungal infection. Scaly, crusty, or red circular patches 1⁄2 to 2 inches (12 to 50 mm) across. Patches show central hair loss with a red ring at the periphery. Sometimes just broken hairs around the face and ears. May become infected. Highly contagious, including to humans.
Stud tail: Greasy, rancid-smelling waxy-brown material at the top of the tail near the base. The site of the glands is usually devoid of hair.