Ferret Adrenal Disease
Dr. Heidi Hoefer
Adrenal disease refers to a hormone-producing tumor of the adrenal gland in the ferret. It is an extremely common condition, usually affecting ferrets over 3 years or age. The adrenal glands are a pair of organs located in the abdomen near the kidneys. In this disease, one or both adrenal glands become hyperactive and start to overproduce sex-steroid hormones, such as androgens and estrogens. The high level of hormones are then responsible for a myriad of symptoms including hair loss, signs of heat, anemia, and problems urinating. Some of these glands become tumors, which can be either benign or malignant. Both tumor types secrete excess hormone. The cause of this condition is unknown but may be related to the unique early development of the adrenals and gonads (ovaries and testes) in the very young ferret. It is thought that perhaps the neutering of juvenile ferrets for the pet trade may interrupt this early developmental pathway and the adrenal gland takes on some of the functions of the gonads. In the U.S., ferrets for the pet trade are typically neutered at less than 6 weeks of age. However, neutering ferrets as adults is gaining popularity, and we now know that even these ferrets can develop adrenal gland disease. So there is still much to learn about this very important disease.
The hormones produced by this condition are responsible for most the problems of adrenal disease. These hormones include estrogen, testosterone, and other androgens (male hormones). The most common effect is hair loss that may be subtle at first, but progresses over time. This hair loss typically starts with the tail and moves forward over the rump and back. Most ferrets are excessively itchy. Some of the hormones result in enlargement of the male prostate gland, or remnant of prostatic tissue in females, and these ferrets have trouble urinating. Bone marrow suppression (anemia) can also result from long-term effects of estrogen. Because these hormones are sex-related, affected ferrets may develop signs of being "in heat", such as a severely swollen and red vulva in females, or increased aggression in males.
Complete urinary tract obstruction can occur with adrenal disease in male ferrets, and occasionally in females. The male hormones produced by the tumor result in prostate enlargement. The prostate then presses on the urethra, the small tube that exits the bladder. Early on, the ferret may strain to urinate, dribble urine, and lick the prepuce. But as the prostate grows, the urethra gets compressed and ultimately, these ferrets cannot urinate at all. This results in a life-threatening situation.
The incidence of Adrenal disease increases with age, making the majority of affected ferrets over 3 years of age. However, younger ferrets can also develop the condition.
The adrenal gland tumor is usually benign, meaning that it doesn't spread to other body locations ("metastasis"). Malignant tumors can grow very quickly, and become large enough to compress other organs, such as the kidneys or intestinal tract. Ferrets with malignant disease may show symptoms one usually associates with cancer, such as weight loss, weakness and muscle wasting. Diagnosis can only be by biopsy and histopathology (microscopic diagnosis).