Stranguria in a Ferret

History. A 6-year-old, male, neutered ferret was presented to a clinic with a history of stranguria, a return to aggressive behavior, and periods of inactivity. According to the clients, the ferret was lethargic and stargazing for 24 hours. The ferret was housed alone, and there were no other pets in the household. Commercial ferret chow and chlorinated tap water were offered daily. Vaccinations (canine distemper virus and rabies virus) were up to date.

Physical examination. The ferret weighed 897 grams and had a body condition score of 2 out of 5. It was quiet, alert, and responsive. Some muscle wasting was evident. An enlarged spleen and two masses were palpated within the abdomen. A firm, nodular mass was palpated cranial and medial to the left kidney, and another large mass was palpated dorsal to the urinary bladder in the caudal abdomen. A pain response was elicited when the caudal abdominal mass was palpated. The urethra was patent, although it was difficult to express the urinary bladder. Physical examination was otherwise normal.

Radiographs. Exploratory laparotomy was performed, and in addition to the splenomegaly and two masses palpated during the physical examination, an additional mass was identified in the pancreas.

Diagnosis. Adrenal gland disease and insulinoma. The caudal abdominal mass was the prostate. Stranguria was attributed to the enlarged prostate. An adrenalectomy was performed, and the histopathologic findings were consistent with an adrenal adenoma. The enlarged prostate was attributed to androgen production from the adrenal adenoma. Although biopsy of the prostate gland can confirm a histopathologic diagnosis, the author does not routinely perform this technique unless primary prostatic disease is suspected.

Hypoglycemia. The weakness and lethargy were attributed to the hypoglycemia. Beta-cell pancreatic tumors are a common finding in geriatric ferrets (> 4 years of age). Ferrets frequently have concurrent adrenal and pancreatic neoplasia. Nodulectomy was performed to remove the pancreatic tumor. The histopathologic findings were consistent with a pancreatic adenocarcinoma.

Muscle wasting. Muscle wasting is a common presentation in the author's practice in ferrets with physiological disturbance, even in the absence of anorexia and with fair body condition scores.The elevated creatine kinase (CK) was attributed to muscle necrosis, whereas the elevated aspartate transaminase (AST) and alanine transaminase (ALT) were attributed to hepatic changes associated with the pancreatic neoplasia. Two liver wedge biopsies were collected at surgery, but the histopathologic findings were unremarkable. Additional samples may have provided more insight into the status of the liver.

Splenomegaly. Splenomegaly is a frequent finding in captive ferrets. Biopsy of the spleen revealed mild extramedullary hematopoiesis.

Recovery from surgery was uneventful. The ferret was reexamined 3 weeks after surgery. The owner reported that the ferret's attitude and behavior had improved. On physical examination, splenomegaly was still present, but the prostate gland was not palpable.

In insulinoma, surgical removal of neoplastic tumors is preferred, although not always corrective. Insulinomas frequently recur. Medical management of insulinoma using prednisone (0.5 to 1.0 mg/kg every 12 hours) and/or diazoxide (10 to 20 mg/kg every 12 hours) should be considered when surgery is not an option or when tumor recurrence is noted. However, management with these drugs is not curative. The prognosis for ferrets with an insulinoma is guarded to poor. The mean survival for ferrets with insulinoma in the author's practice is 14 months.

Surgical approach. Adrenal gland tumors can occur in both glands. Adrenalectomy is the preferred treatment for adrenal gland disease. Right-sided adrenalectomy is more difficult than left-sided surgery because the right adrenal gland is closely associated with the caudal vena cavae. Adrenal gland disease can also be managed with medical therapy. Leuprolide acetate (100 µg/kg every 6 to 8 weeks) has been used with excellent results to control adrenal gland disease in the author's practice. However, similar to medical management of insulinomas, drugs can control clinical disease but are not curative.

Prognosis. The prognosis for a ferret with adrenal gland disease varies and should be based on histopathologic diagnosis. The prognosis for a ferret with adrenal adenoma is fair to poor, while adrenal adenocarcinoma is associated with a guarded to grave prognosis.

Flutamide has been recommended as a chemotherapeutic agent to manage prostate disease in ferrets. However, the author has used the drug in 16 cases and found the results to be unremarkable.

In assessing a ferret with signs of adrenal disease, the practitioner should be alert to the possibility of prostate infection, which is often present. When the prostate is infected, the prognosis is grave. Even after successful adrenal surgery, the ferret will likely continue to have problems urinating and may not recover. Infection was not a component in this case (as indicated by the urinalysis, etc.); thus, surgery was indicated, and the stranguria resolved.

Ask Yourself ...

• What are the problems identified from the history, physical examination, and diagnostic tests?• What is your primary differential at this time?

Did You Answer ...• History/physical examination: stranguria, splenomegaly, two abdominal masses, lethargy/stargazing, muscle wasting, fair body condition• Diagnostic tests:-plasma chemistry analysis: hypoglycemia; elevated AST, ALT, and CK-Radiographs: splenomegaly, prostatomegaly• Insulinoma, adrenal gland disease, enlarged prostate gland, and splenomegaly (nonspecific)