An Overview of Ferret Adrenal Disease
The adrenal glands are located in the abdomen of the ferret. There is one on each side of the abdomen. The adrenal gland’s normal function in the body is to produce hormones that help the body cope with stress (cortisol) and also to produce other hormones that help regulate functions of the kidneys, such as maintaining proper electrolyte balance and the appropriate concentration of the urine. These glands have the potential to produce sex hormones such as estrogen, progesterone, androstrenedione and testosterone. What we are seeing these days is that more and more ferrets have adrenal glands that have been “turned on” and are producing excessive amounts of these hormones. These excessive amounts of hormone cause a wide variety of clinical signs in your pet ferret. The adrenal glands themselves start out as just overproducing hormone, but they can proceed to a precancerous state, a benign cancerous state (adenoma) and then often to a malignant cancerous state (carcinoma). You need to understand this disease process because it has become so common that approximately 80% of all pet ferrets are succumbing to this disease.
- Alopecia (hair loss) – this often starts with the tail and then progresses up the rear end and back. It can be seen in other presentations as well. I had one patient that just had a bald spot as bit as a fifty-cent piece on the top of her head and that was it – she had one of the largest tumors I have ever seen.
- Pruritis – severe itching
- Lethargy – less energy than normal.
- Muscle atrophy – especially over the back and rump.
- Enlarged vulva
- Male aggressive behavior – this can be seen in either male or female ferrets.
- Stranguria (straining to urinate) – This is seen mainly in male ferrets. It is due to the prostate becoming enlarged secondary to excessive testosterone secreted by the adrenal gland(s).
- Polyuria – excessive urination
- Polydipsia – excessive water consumption
- Vomiting – This is often secondary to excessive hair consumption if they are losing hair and grooming themselves.
Our pet ferrets are called Mustela putorius furo. This subspecies of the original ferret never existed in the wild. They were derived from M. putorius (European polecat) with possibly some M. eversmanni (Siberian polecat). Due to overzealous breeding programs, there is not much genetic diversity among pet ferrets in the United States . It is possible that this predisposition to this form of cancer is inherently genetic. There are some current studies being considered to determine the cause of this disease. One is taking a look at the human model of multiple endocrine neoplasia (cancer). In humans this syndrome is caused by a tumor suppressor gene that gets turned off.
Prepubescent spaying and neutering
Dr. Nico Schoemaker in the Netherlands is currently studying how this affects onset of adrenal disease. When an animal is neutered, the negative feedback from estrogen and testosterone on the production of GnRh (gonadotropin releasing hormone) by the hypothalamus (an area in the brain) doesn’t exist anymore. This results in a continuous pulsitile production of GnRH. GnRH stimulates the production of LH (leutenizing hormone) and FSH (follicle stimulating hormone). There are receptors on the adrenal glands for both LH and FSH. The current hypothesis is that the LH and FSH continuously stimulate the adrenal gland. This could be what is causing the hyperplasia formation and tumor.
Currently the one “tried and true” method for dealing with adrenal disease is to surgically excise the affected gland(s). It is not uncommon for both glands to be affected. Note: Remember the adrenal glands have a very important NORMAL function producing cortisol, regulating electrolytes, and urine concentration. If both glands are taken out, your ferret may need to be on a supplement to replace those hormones for the rest of his or her life. This supplement can be provided in a daily liquid.
The most popular alternative to surgery is a medication called Lupron®. This drug acts by stopping the pulsitile secretion of GnRH. The end effect is an inhibition of the production of FSH and LH. There are two different protocols for this drug. One involves a monthly depot injection; the other involves a depot injection once every 4 months (two different kinds of Lupron). The cost works out to be roughly the same. The injections do need to be repeated for the rest of the ferret’s life. Chicago Exotics carries just the one month depot.
Also available through Chicago Exotics is the Suprelorin 4.7mg implant. This implant was originally made for reproduction control in dogs, cats, and horses. It has been found to work in a similar way to Lupron in ferrets. The best part is that it lasts for a whole year. I do not recommend using it in those ferrets with existing prostate enlargement, however. It can cause transient enlargement of the prostate which could be fatal for those ferrets who already have some enlargement of the prostate.
Arimidex works by inhibiting the enzyme that converts androstenedione that is produced by the adrenal glands to estrogen. This drug is potentially useful if the ferret’s adrenal tumor is over-secreting androstenedione that is being converted to estrogen. Both males and females can have excessive estrogen production secondary to adrenal disease. An assay of the ferret’s hormone levels is necessary to determine if this alternative therapy might be helpful for your ferret. We do not recommend this therapy.
One other alternative supplement that has been seen clinically to help males that have stranguria secondary to an enlarged prostate is Saw Palmetto. I have had several clients report back to me with good results with this herbal remedy. Keep in mind though- this is not a cure. It is just palliative treatment to keep a ferret comfortable until arrangements can be made for other treatment. The form I recommend is the alcohol-free elixir at a dose of 3 drops orally twice daily. It is critical that a male ferret on this supplement be observed carefully for the straining to urinate getting worse or a complete lack of being able to urinate. More commonly prescribed for prostate enlargement is the drug Flutamide. I have great success with this drug in controlling prostate growth.
Preventing Adrenal Disease By Exams Every January
Recent research indicates that there are annual treatments that can significantly reduce the risk of your ferret contracting this serious disease. We strongly recommend an annual examination every January for all ferrets where we can administer the prophylactic treatments and make sure your ferret is in tip top shape!
- Johnson-Delaney C: Ferret adrenal disease: Alternatives to surgery. Exotic DVM 1(4):19-22, 1999.
- Johnson-Delaney C: personal communications.
- Schoemaker N: New developments in research on hyperadrenocorticism in ferrets. Exotic DVM 2(3):81-83, 2000.
- Hillyer EV, Quesenberry KE: Ferrets, Rabbits and Rodents- Clinical Medicine and Surgery. Philadelphia, WB Saunders Co, 1997.