Is your ferret losing hair and has skin that appears to be normal? Your pet may be suffering from ferret adrenal gland disease.

Hair will be lost symmetrically (evenly) along the flanks and tail and will proceed along the body wall forward to the head, or the hair may fall out in no specific pattern at all. Approximately 75% of affected female ferrets will also have an enlarged vulva. In about 1/3 of affected individuals there will be intense pruritus (the ferret will be itchy). Approximately 10% of male ferrets affected by the disorder will develop an enlarged prostate which may interfere with the ability to urinate, constituting an emergency situation. Still other ferrets may become sexually aggressive to other ferrets or humans.

In rare, long-standing cases bone marrow suppression may occur with ferret adrenal gland disease. Initially, red blood cell production becomes suppressed and then other blood cell lines may follow (termed a non-regenerative anemia). The bone marrow suppression is believed to be caused by an increase in estrogen.

The portion of the ferret adrenal gland affected by disease is the zona reticularis. The zona reticularis is responsible for the production of the sex hormones. Ferret adrenal gland disease is caused by abnormally high concentrations of circulating concentrations of adrenal gland sex hormones including estrogen, progesterone, androgens, and uncommonly, cortisol. Since cortisol is rarely elevated, this syndrome cannot be described as a Cushing’s type disease.

The cause of ferret adrenal gland disease is currently unknown. Speculations include a link to early neutering and spaying, yet ferrets altered later in life have also been affected. The early alteration causes an abnormal reaction to LH/FSH, leading to enlargement of the adrenal gland and is thereby theorized to increase the amount of hormones produced. Additional theories include the lack of a proper light/dark cycle. Too much light may cause an alteration in melatonin concentrations and thereby lead to abnormal adrenal gland enlargement. Some researches think that decades of inbreeding may have led to a genetic disposition for adrenal gland disease while others speculate that a domestic diet as compared to a wild-type of diet may contribute to the development of the disease.

The adrenals may be unilaterally or bilaterally affected. The adrenals may be affected by either adenomas or adenocarcinomas. Pituitary tumors have never been reported in the ferret. With normal functioning adrenal glands, the production of their hormones is under the control of the pituitary gland. In other species of animals, a tumor of the pituitary gland could lead to the abnormal function of the adrenal glands but this does not occur in the ferret.

The abnormal adrenal gland may produce one or more hormones in excessive quantities. Unfortunately it is not possible to predict which hormones will be elevated in each particular patient. Clinical signs will vary and are dependent on which hormones are being produced.

Ferret Adrenal Gland Disease will need to be differentiated from other sources of hair loss including ectoparasites (fleas, ticks etc.) and dermatophytosis (ringworm fungus). Causes of vulvar enlargement may also include a female being unaltered or being spayed but still having a remnant of ovarian tissue left in the abdomen following surgery.

Definitive diagnosis of ferret adrenal gland disease may be made through the use of abdominal ultrasound revealing abnormal adrenal glands, or the demonstration of elevated adrenal gland hormones. The University of Tennessee has an adrenal hormone panel which measures three sex hormones. High levels of these hormones are highly suggestive of adrenal gland disease, although false negatives may occur.

Medical treatment is used in only non-life-threatening cases and the response to medication varies. Medication will not stop the growth of the adrenal gland and is only palliative. Drugs which have been used include Leuprolide, Arimidex, Flutamide and Melatonin. Most of these drugs may prove expensive for long term usage. Leuprolide is given monthly, or every few months, as an intramuscular injection and will block the effects of LH/FSH on receptors. Arimidex blocks the effects of estrogen and is give by mouth on a daily basis. Arimidex is currently used in human breast cancer treatment. Flutamide is an androgen blocker and is used primarily to reduce prostate size. Flutamide is given once or twice daily. Melatonin is the newest drug being used for the treatment of ferret adrenal gland disease and may be given by mouth or as a pellet implanted under the skin. The method by which melatonin works is unknown. Melatonin may also reduce cortisol concentrations to a dangerous level. Caution should be taken when using melatonin with concurrent insulinoma patients.

The only effective treatment is the removal of the diseased adrenal gland or glands. Surgical removal of the adrenals may be difficult especially when the right adrenal gland is affected and may involve growth into and around the descending vena cava. When all adrenal tissue is removed livelong supplementation with prednisone and a mineralocorticoid are necessary.


References:

Rosenthal, Karen, DVM. “Ferret Adrenal Gland Disease”. NAVC Clinician’s Brief. November 2007. Pp. 89-90.

Lichtenberger, Marla DVM. “Veterinary Clinics of North America, Exotic Animal Practice.” Vol. 10. No.2. May 2007. Pp. 489-490.