Ferret emergency conditions and critical care (Proceedings)

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Ferret emergency conditions and critical care (Proceedings)

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Oct 01, 2008

The ferret patient will often present in an emergency setting with acute presentation of either an acute or chronic disorder. The purpose of this presentation is to review several of the more common ferret emergency conditions, diagnostic modalities, and treatment options. Ferrets as a species are quite amenable to handling, diagnostic testing, surgery and hospitalization. Management recommendations specific for the ferret patient will be discussed.

Hypoglycemia

Hypoglycemia is a common clinical condition in pet ferrets in the United States. Pancreatic islet cell neoplasia (insulinoma) is the most frequent cause of hypoglycemia in the ferret. Other differential diagnoses for hypoglycemia include sepsis, neoplasia, anorexia or starvation, hepatopathy or other metabolic disease.

Ferrets in the age range of two to seven years are most commonly affected. Hypoglycemia related to pancreatic islet cell neoplasia is not common in young ferrets under the age of two years. The initial clinical signs may develop gradually and may not be clinically obvious to the ferret owner. The history may include rear leg weakness, general musculoskeletal weakness, episodes of collapse with hypersalivation, depression, gagging, pawing at the mouth or seizures. Seizures related to hypoglycemia, although quite common in the canine patient, are rare in ferrets. Clinical signs are often intermittent in nature and may not be evident at the time of initial evaluation and physical examination.

A blood glucose level should be measured on any ferret over two years of age presenting to the hospital with the above-mentioned clinical signs. Rapid blood glucose analysis can be performed with either glucose measurement strips or a digital glucometer. It is helpful to also submit part of that same blood sample for evaluation by a clinical pathology laboratory for verification. The normal fasted blood glucose level in the ferret is between 65 mg/dL to 112 mg/dL. A blood glucose level less than 65 mg/dL with accompanying signalment and clinical signs is suggestive of insulinoma. Ferrets with a blood glucose level less than 40 mg/dL may present lethargic, collapsed or comatose. Other blood parameters indicative of insulinoma include an elevated serum insulin concentration (using an assay that has been validated for ferrets) concurrent with hypoglycemia. A definitive diagnosis of insulinoma can only be obtained from histopathological analysis of a surgical pancreatic biopsy.

In cases of hypoglycemic collapse, administer a slow intravenous (IV) bolus of 50% dextrose (0.5 to 2 mL, diluted) to response. The immediate goal of treatment is stabilization and not the complete reversal of the hypoglycemia. Administration of the IV dextrose too rapidly has the potential to stimulate the pancreatic tumor to release large amounts of insulin, resulting in rebound hypoglycemia. After initial stabilization, an intravenous catheter should be placed for fluid support. A constant rate infusion of fluids supplemented with 2.5-5% dextrose should be started. Diazepam can be administered for control of seizures if necessary. Prednisone at a dose of 0.5 to 2 mg/kg PO every 12 hours should be started. The prednisone acts to inhibit peripheral tissue uptake of glucose and stimulate gluconeogenesis . It is best to start with the lowest dose possible to maintain adequate blood glucose level above 70 mg/dL. The dextrose supplementation in the fluids can be adjusted based on regular blood glucose monitoring during hospitalization.

Diazoxide (Proglycem®) is a medication that can also be utilized to treat hypoglycemia secondary to insulin oversecretion2. Diazoxide exhibits hyperglycemic activity by directly inhibiting pancreatic insulin secretion. This action may be a result of the drug's capability to decrease the intracellular release of ionized calcium, thereby preventing the release of insulin from the insulin granules. Diazoxide also enhances hyperglycemia by stimulating the beta-adrenergic system, stimulating epinephrine release and inhibiting the uptake of glucose by cells 3 . Diazoxide can be administered to ferrets orally at a dose of 5 to 30 mg/kg PO every 12 hours 2 . Once clinical signs have resolved, the IV dextrose supplementation can be gradually discontinued. Blood glucose level will need to be monitored after cessation of dextrose supplementation. It is best to keep the ferret hospitalized, if possible, for glucose monitoring at least 24 hours after discontinuation of fluid support. Often, the prednisone dose can be lowered with concurrent administration of diazoxide. Nutritional management is important and should include a high-protein, meat-based ferret or feline diet. Foods high in sugar or carbohydrate content (including treat foods such as raisins) should be avoided. The intake of sugar or carbohydrate based food items could cause an exacerbation of clinical signs by initially causing an increase in blood glucose level and subsequent rebound hypoglycemia.

A small number of ferret patients with seizure activity may be refractory to medical treatment alone. Ferrets unable to maintain normal blood glucose level once dextrose supplementation is discontinued may require surgical intervention. These ferrets, once stabilized, may require surgical debulking of the pancreatic tumors. Debulking may assist with management of this disease, but is not curative. Many ferrets, however, may not have visible pancreatic nodules. There is potential for microscopic disease in the pancreatic tissue. The average life expectancy with medical and/or surgical therapy after the development of persistent hypoglycemia is approximately 8-12 months.