Introduction

• Cause: currently unknown.
• Signs: variable from lethargy, slight incoordination (ataxia), stargazing and weakness in the hind limbs to complete collapse, generalized seizures and coma.
• Diagnosis: blood biochemistry, diagnostic imaging, exploratory surgery.
• Treatment: pancreatectomy, glucocorticoids.
• Prognosis: better compared with dogs, in which metastases are very common.
• Insulinomas or islet cell tumors are, usually, small (0.5-2 mm) tumors of the pancreatic beta cells.
• Results in the production of excessive amounts of insulin and subsequent hypoglycemia.
• Tumor types may be described as hyperplasia, adenomas or carcinomas.
• Most are well circumscribed, but infiltration in surrounding tissues may occur.
• In contrast to dogs, insulinomas in ferrets rarely metastasize.

Pathogenesis

Etiology

• The etiology of insulinomas in ferrets is currently unknown.
• The limited genetic diversity of ferrets, which stem from a limited number of breeder farms, has led to the suggestion that a genetic component may be involved.
• Another theory suggests that, based on the natural carnivorous diet of mustelids, diets high in carbohydrates may contribute to the development of these tumors.
• A diet high in protein (42-55%  on a dry matter basis), high in fat (18-30% on a dry matter basis), low in carbohydrates (8-15% on a dry matter basis), and low in fiber (1-3% on a dry matter basis) has therefore been advised to reduce the incidence.
• Alternatively, feeding commercial balanced diets based on entire prey animals has been recommended.
• No scientific evidence, however, is available to back up any claims on the etiology of insulinoma, nor has it been proven that the incidence is reduced when ferrets are fed prey based diets or low-carbohydrate kibble.
• The 'modern' keeping of ferrets (early neutering, kibble diet, indoor housing and probably certain genetics) is associated with a higher incidence of insulinomas when compared with other classic husbandry practices. Geographical differences in incidence are believed to be caused by differences in these factors.

Pathophysiology

• Most ferret insulinomas express insulin, chromogranin A and neuron-specific enolase.
• Most ferrets diagnosed with insulinoma have between 1 and 5 nodules.
• Most nodules (56%) are in the left lobe of the pancreas (30% on the right lobe and 14% on the body of the pancreas).
• Very low rate of metastases; about 7% of tumors metastasize to regional lymph nodes, liver and spleen.
• A large number of ferrets (85%) that present with insulinoma have concurrent disease: splenomegaly, adrenal tumors, cardiomyopathy, stomach hair balls, lymphoma, etc.
• Hyperplasia, adenoma and adenocarcinoma are the most common histologic changes.

Epidemiology

• Prevalence is considered 20-25% of diagnosed ferret neoplasms.

Diagnosis

Treatment

Prevention

Outcomes