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Veterinary Medicine
Instructions for Veterinary Clients

Endocrine Alopecia
From Duclos: Canine and Feline Skin Diseases

General Information

Alopecia means hair loss. When alopecia is seen with no scratching, rubbing, biting, or licking, the cause is usually a result of some disruption in normal hair growth. Endocrine alopecia refers to hair loss caused by an excess or deficiency in hormones. The normal hair cycle includes phases of growth, rest, and shedding. Each of these phases is controlled by various growth factors; some are known to be hormones, but many of the growth factors are currently unknown. If the growth part of the cycle is defective, new hairs fail to grow, and the entire hair cycle stops. Control of the hairs varies with different parts of the body, so hair loss can be seen in one part while the hairs on the rest of the body are normal. The length of each part of this cycle varies with age, breed, and the part of the body affected. Many factors affect the hair cycle, including the length of day (season), nutrition (vitamins, minerals, protein), hormones (estrogen, testosterone, thyroid, cortisol), and other internal signals (growth factors).

When an animal has endocrine alopecia, most of the hairs on the trunk and tail are affected. A deficiency in testosterone, thyroid, or estrogen and an excessive amount of cortisol can cause endocrine alopecia. The pattern of hair loss caused by hormone problems is characterized by hair loss on the trunk and tail; the head and legs are spared.

Important Points in Treatment

  • Diagnosis is made by history, physical examination, and blood tests. Biopsies can be taken but are usually not needed.
  • Treatment can only be achieved after the cause is determined.
  • Some forms of endocrine alopecia do not respond to treatment.
  • Replacement hormones may be necessary.
  • Removal or prevention of the excess in cortisol or corticosteroids may be necessary.

Treatment Instructions

Notify the Doctor if Any of the Following Occur

  • The animal drinks an excessive amount of water, urinates frequently, has an increased appetite, and is lethargic.
  • The animal shows signs of itching, biting, or chewing.
  • Pet develops sores, bumps, and crusts on multiple spots on the skin.

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