A number of whole-body diseases also affect the skin. In some instances, the skin changes are characteristic of the particular disease. Often, however, the signs are not obviously associated with the underlying condition and must be carefully distinguished from primary skin disorders. Some of these secondary disorders are mentioned briefly below and are also described in the chapters on the specific disorders. Some skin disorders may be associated with a poor diet. However, this is uncommon in cats fed modern, balanced diets.
Dermatitis (skin inflammation) is sometimes seen in association with disorders of internal organs, such as the liver, kidneys, or pancreas. Liver disease and diabetes can rarely cause death of skin tissue in old cats. The skin changes include redness, crusting, oozing, and hair loss on the face, genitals, and lower legs, as well as thickened skin and ulcers of the footpads. Itching and skin infections can also occur in cats with diabetes. The skin disease may be noted before the onset of signs of the internal disease.
Fragile skin syndrome (the skin becomes very fragile and is easily broken) in cats has been associated with pancreatic, liver, or adrenal disorders. Pancreatic cancer may cause crusting of the footpads and hair loss in cats.
Mild hair loss can occasionally occur after spaying or neutering in cats. The hair loss typically occurs near the genitals and does not appear to be itchy.
Hypothyroidism (low levels of thyroid hormone, is very rare in cats. The disease can cause skin changes with diminished hair growth and hair loss. The skin is dry, scaly, thickened, and folded. Secondary skin infection and seborrhea (oily dandruff) may occur.
Hyperadrenocorticism (high levels of adrenal gland hormones) also causes skin changes such as darkening, hair loss, seborrhea, and secondary infection. In cats, the skin becomes extremely fragile.
Treatment of all these conditions depends on identifying and treating the underlying disease. The earlier in the disease process your veterinarian can examine your cat, the more rapidly a diagnosis may be obtained and an outcome predicted for the animal.
Also see professional content regarding systemic dermatoses.