Adrenal Disease In Ferrets
Adrenal Gland Tumors and
|I wrote this article some time ago. Since then, the most effective non-surgical treatments for adrenal gland disease in ferrets has proven to to be implants of materials (GnRH agonists like Lupron and deslorelin) that block your ferret's pituitary gland production of the hormone LH - thought by many to be the underlying cause of ferret adrenal gland tumors. But another option may soon be available as well, a vaccine, GonaCon, that immunizes ferrets against their own GnRH hormones. It is unclear if it will be as effective as the implants or when it might become available in the USA. As of 2013, its availability is limited to USDA-approved attempts to use its birth control effects to control stray dog numbers on Indian reservations. But the vaccine may even have the potential to prevent ferret adrenal gland disease from ever occurring. What side effects it might also cause are as yet unknown. You can read about GonaCon's use in ferret adrenal gland disease here.|
Ron Hines DVM PhD
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Ferrets make wonderful pets. Unfortunately they age more quickly than dogs or cats do. A 12-year old ferret is an exceptionally old ferret. Very few live that long.
There are two reasons for this:
Genetics is one. None of the ferret's small wild relatives live more than 7-10 years.
But these pet's lives are also shortened by a relatively small number of diseases that are verry common in ferrets. One of the most common are adrenal gland tumors. Both sexes get them - it is slightly more common in females than males. Some of these pets are as young as 3 years old.
Why Do Ferrets Get Adrenal Gland Tumors?
Some people think that the problem is due to the small gene pool of American ferrets. Most American ferrets are derived from a small number of animals obtained by George Marshall in the 1950’s. It may be that the inbreeding that resulted, increased the animal’s susceptibility to these tumors.
Others feel that the practice of neutering ferrets very young is the cause of this disease. It does not appear to be as common in Scandinavia where ferrets are often left un neutered. Neutering ferrets removes the target organs (ovaries, testicles) for hormones (GnRH) produced by the pituitary gland within the brain. Since this gland no longer has circulating blood products to keep it in check, it produces an excess of hormone, which is closely related to the hormone that naturally stimulates adrenal gland activity (ACTH). After years of stimulation, the adrenal glands may become cancerous or simply enlarged and hyperactive. In either case, it then produces abnormally high levels of female (estrogenic) and male(androgenic) hormones. I tend to think this second explanation is the most likely. This condition must not be confused with the normal seasonal hair loss that occurs in un-spayed female ferrets during their heat cycle.
Endocrine Disrupting Chemicals
Today's environment and food supply are packed with manmade compounds. Some of thes, called endocrine disrupting chemicals, are suspected of causing endocrine glands to run amuck in many species. There is a lot of evidence that one group, PBDEs are involved in thyroid hormone overproduction in cats. Hyperthyroidism in cats and hyperadrenocorticism (overactive adrenal glands) in ferrets have many similarites. These chemicals are very similar to hormones that tell the body's endocrine glands how much hormone to produce. When these glands over produce, the end result is often a tumor of the gland. Other chemicals that have been implicated in these type of problems are BPAs and others that are commonly found in plastics. They all eventually enter the water and food supply of humans and animals.
What Are The Signs Of Adrenal Gland Disease In My Ferret?
The first sign that something is amiss is a thinning of hair near the tip of your ferret's tail.
The pet's adrenal gland has begun to produces abnormally large quantities of steroids that result in a thin hair coat and a thin skin among other things.
Later, hair fails to grow over the ferret's back and on its stomach. In females, the area surrounding the vagina (vulva) becomes swollen, due to too much estrogens in her system.
Approximately one in three ferrets with this problem will be itchy. This hair loss is always symmetrical, that is, the same on either side. It is not so much that the hair is falling out, it is that it is not being replaced and wears off at the points on the pet's body that rub most.
There is no other condition that will result in these signs. These ferrets are also underweight; their skin is wrinkled and very thin.
They do not appear to be in pain, but some are less energetic than they ought to be. Many loose muscle mass - especially in their thighs and rear.
Some will become more aggressive.
Some male ferrets with this underlying problem will have trouble passing urine due to an enlarged prostate gland.
Some appear to drink and urinate more.
I diagnose these cases by having a urine androgen/estrogen test performed by Texas A&M University or send a sample to the University of Tennessee for an adrenal hormone panel. Many times, the tumor(s) can be seen in an ultrasound examination. But very small tumors are not detectable by ultrasound. If your ferret shows the distinctive hair and skin changes of an adrenal gland tumor - it is likely to have the problem even if the ultrasound examination was negative.
When the diagnosis is confirmed, there are several ways the problem can be treated.
A non-surgical approach is to administer one of a number of "anti-hormones" to the ferret every 4-6 months. These anti-hormones are called GnRH inhibitors. Two that I have used successfully are luprolide acetate (Lupron, TAP Pharmaceuticals) and Goserelin (Zoladex, Zeneca Pharmaceuticals) implants. When these drugs are administered, hair coat re grows and blood levels of the problem hormones falls. However, the adrenal tumor remains and the shots must continue every 6 - 8 months indefinitely.
In August, 2012, Virbac Animal Health announced that it had obtained permission from the FDA to market a GnRH deslorelin implant (Suprelorin F) for ferrets with adrenal gland tumors. It was previously available only in Australia and certain parts of Europe. Virbac indicated that a single implant might control ferret adrenal gland disease for an entire year. (ref)
A less expensive - but not as effective - way to treat your ferret is with mitotane (Lysodren), which must be given orally every three or four days. This medication attacks the tissue of the adrenal gland. It is used primarily in pets to control over active adrenal glands in dogs (Cushing's Disease) . Mitotane has a number of unwanted side effects. I do not recommend that it be given.
Melatonin is another drug that has been given to ferrets with adrenal gland disease. Melatonin is one of the chemicals that regulate pituitary cycles. Perhaps it will have some value in ferrets. It is apparently safe and it is readily obtainable by ferret owners. However, it is very unlikely that it will cure the disease. When it is naturally produced in your pet, it's level pulses in the blood stream quite differently than when it is given as a tablet. It has been formulated as a patch and a cream to try to get around this. It was once produced as an implant for mink.
The only curative treatment at this time is to surgically remove the tumors. They are generally quite visible within the body of the adrenal gland or glands and can be desiccated (zapped) with an electrocautery (electric knife) or lazer. This surgery is considerably easier when the left adrenal gland is only involved. The right adrenal gland is farther forward and much harder to approach without damaging the large blood vessels around it. . I always check the ferrets pancreas during adrenal surgery. Sometimes I will remove pancreatic tumors during the same procedure.
When the veterinarian finds that both adrenal glands have tumors, we sometimes remove the left one and the portion of the right one that we can get at. This is called "de bulking". It retards the disease but does not permanently cure it. If we remove both glands completely, the ferret will need replacement hormones for the rest of its life.
What If I Do Not Treat The Problem?
Ferrets with this problem do not appear to be in pain. Some of them do appear weak. These are probably anemic. Without surgery, your ferret might live six month to two years.
Because the pituitary gland of your ferret is partially under the control of sunlight, some ferret owners give their ferrets lots of exposure to natural sunlight to try to keep the pets biological rhythms synchronized. Perhaps this might help. The effects of sunlight on hair growth and biological rhythms is complex. (ref) It operates through a compound called melatonin, produced in the pet's pineal gland and retinas.
Anastrozole (Arimidex) used to treat breast tumors in postmenopausal women has also been tried in ferrets with adrenal tumors. It has not been effective long term in any of the cases I know of.
Some ferret owners have given their male ferrets with this problem saw palmetto to help them urinate . I do not know what the results have been.