Case Description—A 7.5-year-old spayed female ferret was evaluated because of weight loss despite a good appetite. Pancreatic insulinoma had been diagnosed at another animal hospital on the basis of detection of low blood glucose concentration on 1 occasion; however, concurrent determination of blood insulin concentration was not performed. The ferret had been treated SC with methylprednisolone acetate (unknown dosage) every 30 days for 2 years. No follow-up data regarding blood glucose concentration were available.
Clinical Findings—On physical examination, the ferret was thin (weight, 0.619 kg [1.36 lb]) and bruised easily. Serum biochemical analysis revealed hyperglycemia (blood glucose concentration, 855 mg/dL; reference range, 63 to 134 mg/dL).
Treatment and Outcome—Glucocorticoid injections were discontinued, and the ferret was administered prednisolone (1.13 mg/kg [0.51 mg/lb], q 12 h for 14 days, then 0.56 mg/kg [0.25 mg/lb], q 12 h for 7 days) orally. After prednisolone administration was discontinued, hyperglycemia and weight loss persisted. The ferret was administered insulin glargine (0.5 U) SC; blood glucose concentration was monitored every 2 hours for 24 hours, at which time the value had decreased to nearly within reference range. The owner continued insulin glargine administration at that dose every 12 hours; after 77 days of treatment, the ferret's weight was 0.731 kg (1.61 lb), which was considered normal, and blood glucose concentration was within reference range.
Clinical Relevance—Regular SC administration of insulin glargine was successful in the treatment of diabetes mellitus in the ferret of this report and may be effective for other diabetic ferrets.
Case Description—A 5-year-old male guinea pig (Cavia porcellus) was examined because of lethargy, weight loss, and episodic neurologic signs, including paddling in lateral recumbency, head tilt, and circling. Prior to initial examination, the animal was treated with corn syrup whenever it appeared lethargic, plus an unknown dosage of sulfadimethoxazole.
Clinical Findings—The animal was thin, with abdominal distention and subtle torticollis. Chemistry panel results documented hypoglycemia (45 mg/dL). Corn syrup was discontinued in favor of a high-fiber formula fed via a syringe. Measurement of blood insulin concentration demonstrated hyperinsulinemia (> 1,440 pmol/L [> 201 μU/L]), with concurrent hypoglycemia (0.6 mmol/L [11 mg/dL]).
Treatment and Outcome—Diazoxide treatment for presumptive insulinoma was started at a dosage of 5 mg/kg (2.3 mg/lb), PO, every 12 hours. A blood glucose curve demonstrated persistent hypoglycemia, and the diazoxide dosage was gradually increased to 25 mg/kg (11.4 mg/lb), PO, every 12 hours. A second glucose curve measurement 12 days later confirmed adequate euglycemic control. Three weeks after the initial diazoxide dosage increase, the animal was reexamined for constipation and abdominal distension and died the following day. Histologic analysis confirmed a pancreatic beta-cell tumor (insulinoma).
Clinical Relevance—To the authors' knowledge, this is the first report of premortem diagnosis and treatment of an insulinoma in a guinea pig. This case demonstrates that diazoxide treatment can help achieve euglycemia in hypoglycemic guinea pigs and is a potential treatment option for guinea pigs with insulinoma.