Two hormonal (endocrine) disorders, insulinomas and hyperadrenocorticism, are common in ferrets.
An insulinoma is a tumor of the pancreas. These tumors are very common in ferrets older than 3 years of age. Insulinomas produce more insulin than the body needs. The elevated insulin levels result in low levels of blood sugar (hypoglycemia)—a condition that is the opposite of diabetes. Ferrets with insulinoma have signs such as:
slight or partial paralysis of the rear legs
teeth clenching or grinding
In severe cases, seizures may occur. Diagnosis is based on evidence of hypoglycemia along with corresponding normal or elevated insulin levels. This is done using a fasting glucose test. You will be asked to withhold food from the ferret for about 4 hours before the appointment; a blood sample will then be drawn during the visit. Other bloodwork results are usually normal. Ultrasonography only occasionally reveals these tumors.
Medical and surgical treatments are possible, but there is no cure. Surgical treatment involves removing either the mass alone or the part of the pancreas where the mass is located. Because some insulinomas occur as multiple tiny tumors scattered throughout the pancreas, surgery may not remove all of the cancer. Some ferrets have a period of normal blood glucose (sugar) levels after surgery, but most ferrets require continued medical treatment. The benefits of surgery include reducing the severity of signs, easing management, and moderately increasing survival time. Medical treatment to counteract the effects of the tumor is lifelong and does not directly shrink the tumor. Ferrets with insulinomas need blood glucose tests every few months and after changes in medication doses.
If your ferret shows signs of hypoglycemia (weakness or collapse), you can try offering a little honey or corn syrup. For safety, do not put anything in the mouth of a ferret having a seizure. Ferrets with signs of hypoglycemia should be seen by a veterinarian immediately.
Hyperadrenocorticism in ferrets is caused by overproduction of sex hormones (progesterone, testosterone, and estrogen) by the adrenal gland. It can be seen in ferrets as young as 1.5 years old. Having your ferret spayed will help prevent this disease. The most common sign is hair loss beginning on the tail and rump and progressing up the body toward the head. Female ferrets may also have a swollen vulva and enlarged nipples. Male ferrets may become aggressive and have difficulty urinating due to an enlarged prostate gland. Bone marrow suppression may follow severe elevation of estrogen levels in the blood in either sex. Ferrets with these signs should be taken to a veterinarian as soon as possible.
A veterinarian will make a preliminary diagnosis based on the history and physical examination of the ferret. The enlarged adrenal glands may be felt in front of the kidneys. Routine blood test results are usually normal. Ultrasonography may show enlarged glands, but your veterinarian needs to measure the sex hormones to make an accurate diagnosis.
Treatment for this condition includes medical and surgical options. Surgical removal of the adrenal gland(s) is more likely than medical management to cure the disease, but the disease will return in about 40% of all affected ferrets. If both sides are affected, the adrenal glands can be partially removed.
An examination of gland tissue may reveal that the disease has progressed to 1 of 3 levels: hyperplasia, adenoma, or adenocarcinoma (cancer). Functionally all 3 grades are similar, and the spread of cancer cells outside the glands is unlikely. Because the adrenal glands produce other hormones needed by the body, ferrets that have both adrenal glands completely or partially removed may develop other problems due to a lack of those hormones. These conditions can be treated with medications.
Signs can be reduced through medical management, but such treatment does not shrink the adrenal gland tumor causing the problem. Medical management must continue for the rest of the ferret's life to control the signs of disease. Ferrets should be closely monitored if longterm medical treatment is used. Melatonin can be used to treat hair loss and may help manage other signs as well. Other drugs used to control sex hormone levels in humans are beginning to be used in ferrets and show promise in controlling the signs.