Dear Frank B. Ferret: Ferdinand, my 4-year-old ferret, is losing the hair on his tail. He doesn’t have fleas, and he seems fine except for his hair loss. My other ferret’s hair is normal. What is causing Ferdinand’s hair loss?

Frank Responds: Like Ferdinand, many ferrets over three years of age lose hair from the tail and back. Typically, the hair loss is symmetrical and the skin looks normal, without redness or bumps, though it may be itchy.

The condition, called hyperadrenocorticism, is caused by enlargement of the adrenal glands, two small organs near (“ad-“) the kidneys (“-renal”). The result is over-production of the sex hormones secreted by the adrenals.

Additional clinical signs may include enlargement of the vulva in spayed females and the prostate in neutered males. The enlarged prostate may cause frequent, painful urination and even urinary obstruction. Some ferrets with adrenal disease exhibit increased sexual behavior and aggression.

If the diagnosis is unclear, adrenal disease can be confirmed by abdominal ultrasound or blood tests to look for elevated hormone levels.

Treatment options include surgical removal of the affected adrenal gland(s) or injection of a long-acting drug such as deslorelin or leuprolide.

To find out for sure what’s causing Ferdinand’s hair loss and learn about options for treating the problem, make an appointment with a veterinarian experienced with ferrets.