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Adrenal Disease

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"My ferret is losing its hair."

While hair loss in the ferret can occur from many causes, I would like to concentrate on what is the most common and what is becoming the most commonly talked about reason for serious hair loss -- proliferative lesions of the ferret adrenal gland.

Ferrets with adrenal lesions - including areas of hyperplasia as well as both benign and malignant neoplasms of the adrenal cortex - typically all show the same clinical signs regardless of which type of growth is present. These signs are fairly diagnostic, and in the majority of cases, are so characteristic that no other diagnostic tests are required before therapy is instituted.

The signs of adrenal disease in the ferret are well documented (Fox et al., 1987, Lawrence et al. 1993, Rosenthal et al., 1993, Lipman et al, 1993) although the cause of these signs is still somewhat unclear. Adrenal lesions may be seen in animals ranging from one to seven years of age, with the average being around 3.5 years. In one study (Rosenthal, 1993), 70% of affected ferrets were female. Hair loss, or alopecia, is by far the most common clinical sign in affected ferrets. Hair loss often begins at the tail, and progresses forward over the trunk, flanks, and abdomen, until hair is only present on the neck, head, and the extremities. Additionally, in spayed females, the vulva will often become swollen to the extent that the owner may erroneously believe that the animal is in estrus. A watery mucus discharge from the vulva may also be seen in this animal. (Vulvar swelling in a spayed female on its own is sufficient cause to warrant abdominal exploratory surgery). Other clinical signs that may be seen in ferrets with adrenal lesions include increased scratching, excessive drinking and urination, anemia, weight loss, and in long-standing cases, difficulty in using the hind legs.

The cause of the hair loss and vulvar swelling is not currently known. In other species with hyperadrenocorticism, high circulating levels of adrenal corticosteroids cause the hair follicles to atrophy and the skin itself to become thin, resulting in hair loss. But since we know that these ferrets do not have these high levels of cortisone, this explanation does not suffice for what we see clinically. A plausible theory has been advanced by specialists at the Animal Medical Center in New York City. (Rosenthal, 1993). Citing the fact that 36% of affected ferrets have high blood levels of estrogen, the believe that early neutering (most ferrets in the U.S. are neutered before six weeks of age) cause a population of cells in the adrenal gland which have retained the ability to secrete gonadal hormones to grow, in essence "filling the void". High levels of estrogen are well known to also cause hair follicle atrophy, and would also cause vulvar swelling in females, as is seen in estrus. In fact, Dr. Rosenthal has demonstrated that serum estrogen levels are indeed higher in ferrets with adrenal disease.

The treatment for adrenal disease in ferrets primarily involves removal of the affected adrenal gland. [If money is an object, Dr. Tom Kawasaki in Woodbridge VA, will probably do it for less than $300 (and he has done many more than most vets).] In most cases, adrenalectomy is performed based solely on clinical signs. Routine pre-surgical blood work should be performed in all animals over 4 years of age, as would be done for any other type of surgical procedure. Special diagnostic tests which are used in other species to diagnose adrenal disease are rarely of use in the ferret. Specific testing for estrogen levels in the ferrets is not commonly available, even at diagnostic labs, and in most cases is not necessary to confirm the diagnosis.

In most cases, one gland is noticeably larger than the other and is removed. For unknown reasons, the left adrenal gland accounts for the majority of lesions (64%), with the right adrenal gland accounting for 26%, and 8% of ferrets having disease in both adrenals. Removal of one adrenal gland is generally well tolerated in ferrets and in most of these cases, if disease is confined to that gland, clinical signs will cease (i.e., the hair will grow back and the swollen vulva will diminish to its previous size). In animals with bilateral disease, removal of one gland and part of another has been done, but carries a more significant risk of post-operative complications.

The surgery itself is not excessively difficult. Removal of the left adrenal is fairly easy and has a low risk of complication. Due to the position of the right adrenal near several large blood vessels, it is a more difficult surgery and requires considerably more expertise on the part of the surgeon. As always, if your veterinarian has little expertise in performing this surgery, it is wise to ask for a referral to a more experienced surgeon. In cases in which surgical excision of the offending adrenal gland is not an option, medical treatment with certain drugs that kill off a large portion of the cells of the adrenal cortex may be tried. Unfortunately, this medication is not specific for estrogen-secreting cells, and affect all of the other cortical cells as well. For this reason, this form of treatment should be reserved only for those animals who are poor surgical candidates.

Unfortunately, not all adrenal surgeries end happily. Postoperative mortality averages from 10% (Tom Kawasaki, personal communication) to 12.5% (Rosenthal, 1993). The cause of the post-surgical mortality is not known; most theories center on the inability of the other, unaffected adrenal gland to produce enough cortisol on short notice, i.e., the hyperfunctioning gland has caused it to atrophy.

On a personal note - while some owners believe that hair loss is only cosmetic and would "rather not put their pet through the stress of an operation", let me categorically state that the changes seen in ferrets with adrenal disease are cumulative and progressive. Animals with adrenal lesions do not just lose their hair - they also lose muscle mass, and have little energy. While the lesions themselves are rarely life-threatening (in over one-hundred twenty cases, I have only seen two cases of tumor metastasis), their clinical manifestations are debilitating and greatly decrease the quality of a ferret's life. (When I noticed the signs of adrenal disease in one of my ferrets who was six at the time - I had the surgery done immediately. The hair has grown back, the vulva has reattained its normal size, and she is more fit than ever.)

Adrenal disease in the ferret is common, and if detected by a watchful owner or a knowing practitioner, can be easily treated.

Get those hairless ferrets checked, and have a festive ferret-filled holiday season.

1. Fox J.G, et. al. Hyperadrenocorticism in a ferret. JAVMA, 191: 343, 1987.

2. Lawrence, H.J. et al. Unilateral adrenalectomy as a treatment for adrenocortical tumors in ferrets: Five cases (1990-1992). JAVMA 203: 267-270, 1993.

3. Lipman, N.S. et al. Estradiol-17B-secreting adrenocortical tumor in a ferret. JAVMA 203(11): 1552-1554, 1 Dec 1993.

4. Rosenthal, K.L. et al. Hyperadrenocorticism associated with adrenocortical tumor or nodular hyperplasia of the adrenal gland in ferrets: 50 cases (1987-1991). JAVMA 203: 271-275, 1993.

Bruce Williams, DVM

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