A 7.5-year-old female spayed ferret weighing 0.619 kg (1.36 lb) was evaluated at the Veterinary Center for Birds and Exotics, Bedford Hills, NY, because of weight loss despite a good appetite. A diagnosis of pancreatic insulinoma had been made previously by another veterinarian on the basis of a single measurement of hypoglycemia (determined with a handheld glucometer); that assessment had been performed without concurrent evaluation of blood insulin concentration. 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 had been obtained.
On initial evaluation, the ferret was thin, had muscle wasting, and bruised easily. The owner reported that the ferret was eating well but losing weight and appeared weak. A 0.3-mL sample of blood was collected from a lateral saphenous vein and analyzed within 5 minutes after collection. Serum biochemical analysis, performed with an in-hospital, tabletop serum biochemical analyzer,a revealed hyperglycemia (blood glucose concentration, 855 mg/dL; reference range, 63 to 134 mg/dL1) and mild azotemia (creatinine concentration, 0.9 mg/dL [reference range, 0.2 to 0.6 mg/dL1]; BUN concentration, 45 mg/dL [reference range, 12 to 43 mg/dL1]). Results of a CBC, performed with an in-hospital tabletop analyzer,b were unremarkable.
Glucocorticoid injections were discontinued, and treatment with prednisolone sodium phosphatec at gradually tapering dosages (1.13 mg/kg [0.51 mg/lb], PO, q 12 h for 14 days, then 0.56 mg/kg [0.25 mg/lb], PO, q 12 h for 7 days) was initiated to wean the ferret slowly off exogenous corticosteroids. One week after commencement of oral prednisolone administration, the ferret remained hyperglycemic (blood glucose concentration, 473 mg/dL) and continued to lose weight (weight, 585 g [1.28 lb]). It had been hoped that the hyperglycemia would be transient and would resolve after the oral prednisolone administration was discontinued. However, 2 weeks later (when oral prednisolone administration was discontinued completely [ie, 3 weeks after the initial evaluation]), the ferret appeared clinically stronger and continued to eat well but remained hyperglycemic (blood glucose concentration, 535 mg/dL).
After discontinuation of oral administration of prednisolone, measurement of blood glucose concentration during a 24-hour period was planned. However, the owner lived some distance from the hospital and was unable to return the ferret for assessment until 3 weeks later (ie, 6 weeks after its initial evaluation). At this point, a 24-gauge IV catheter was placed in the right cephalic vein for blood sample collections. A baseline blood sample (0.3 mL) was analyzed within 5 minutes after collection with the same in-hospital, tabletop serum biochemical analyzer used previously; analysis revealed that the ferret was hyperglycemic (blood glucose concentration, 840 mg/dL). Insulin glargined (0.5 U [measured in a U-100 syringee marked in 0.5-U increments) was administered SC between the ferret's scapulae, and a 0.3-mL blood sample was collected with the catheter every 2 hours for 12 hours by the same person, who processed each sample through the same serum biochemical analyzer within 5 minutes after sample collection. Fourteen hours after the first injection, a second dose of insulin glargine (0.5 U, SC) was administered between the scapulae by the same individual who administered the first dose. A 0.3-mL blood sample was collected for analysis via the catheter every 2 hours for an additional 18 hours (Figure 1). During the entire assessment period, the ferret was confined to a small cage and had access to both dry ferret kibble and a high-protein liquid food formulated for syringe feeding to carnivorous animals. The ferret grazed on food and slept intermittently during the assessment.
After completion of 22 hours of the blood glucose concentration assessment, the ferret's blood glucose began to rise dramatically; thus, the ferret was administered an additional dose of insulin glargine (0.5 U, SC) between the scapulae. Additional blood samples were then collected every 2 hours for a total of 32 hours. The ferret was then discharged from the hospital and returned to the care of the owner, who was instructed to administer the insulin at the same dosage and in the same manner as it had been given thus far. The owner also was instructed to monitor the glucose concentration in urine voided in the ferret's paper-lined litter box with commercially available urine dipsticksf as often as possible and to continue to administer insulin glargine (0.5 U, SC, q 12 h) if the dipstick test revealed greater than trace amounts (5.5 mmol/L) of glucose in the urine.
The owner continued administration of insulin glargine (0.5 U, SC, q 12 h) between the scapulae for an additional 18 days; during that period, the glucose concentration of the ferret's urine was assessed by use of urine dipsticks at least twice daily, at 12-hour intervals whenever possible, before the next dose of insulin glargine was administered. Results of the dipstick assessment revealed that the ferret's urine was never completely glucose free; on most occasions, the urine was moderately positive (14 mmol/L) for glucose. To reduce the likelihood that the ferret would become hypoglycemic after the owner administered insulin and had to leave for work, the owner ensured that the ferret consumed a meal within minutes after receiving the injection.
Eighteen days after the initial administration of insulin glargine during the first blood glucose concentration curve, the ferret was returned to the hospital. It was eating well, was active, and had gained weight (weight, 0.649 kg [1.43 lb]). A 24-gauge catheter was placed in the left cephalic vein, and a 0.3-mL blood sample was collected via the catheter every 2 hours for 8 hours by the same individual who had performed the previous blood glucose assessment. The owner had administered insulin glargine (0.5 U, SC) between the scapulae approximately 2.5 hours before the first blood sample was collected. The initial blood sample and 4 additional 0.3-mL samples were analyzed with the same in-hospital biochemical analyzer as before; data were used to generate a second (abbreviated) blood glucose concentration curve (Figure 1). During this 8-hour assessment, the ferret was similarly confined to a small cage and had access to both dry ferret kibble and a high-protein liquid food formulated for syringe feeding to carnivorous animals.
The ferret was discharged from the hospital and returned to the care of its owner, who continued administering insulin glargine (0.5 U, SC, q 12 h) between the scapulae when the dipstick assessments revealed greater than trace amounts of glucose in the urine. The ferret continued to eat well and gain weight, and after an additional 2 weeks of insulin glargine treatment, the owner less frequently documented that the ferret's urine was moderately positive for glucose.
Eighty-four days after the initial evaluation and 42 days after the initial administration of insulin glargine, the ferret was reevaluated at the hospital. Its weight was 0.695 kg (1.53 lb). A blood sample was collected approximately 4 hours after the ferret had received the morning dose of insulin glargine; analysis performed in the same manner and with the same in-house serum biochemical analyzer used previously revealed the ferret's blood glucose concentration was within reference range (82 mg/dL).
One hundred nineteen days after the initial evaluation and 77 days after the initial administration of insulin glargine, the ferret had gained weight (weight, 0.731 kg [1.61 lb]) and its blood glucose concentration was at the low end of the reference range (67 mg/dL). The owner reported the ferret was more active and energetic than ever before and that no glucose was detected in the ferret's urine with the dipsticks, even up to 72 hours after administration of a dose of insulin glargine. The owner continued to monitor urine glucose concentration with urine dipsticks at least twice a day (at approx 12-hour intervals). However, because the dipstick readings revealed no glucose in the urine more frequently than they had previously, the owner no longer administered insulin glargine every 12 hours but rather whenever the dipstick reading was greater than trace amounts (5.5 mmol/L) of glucose in the urine.
The ferret was returned to the hospital 100 days after the initiation of insulin glargine treatment. The ferret was doing well clinically and weighed 0.8 kg (1.76 lb). A 24-gauge catheter was placed in the right cephalic vein, and a 0.3-mL blood sample was collected with the catheter every 2 hours for 8 hours by the same individual who had performed the previous blood glucose assessment. The initial blood sample and 4 additional 0.3-mL samples were analyzed in the same in-hospital chemistry analyzer as before; data were used to generate a third (abbreviated) blood glucose concentration curve (Figure 1). When this third assessment was begun, the ferret had not received any insulin for 72 hours and the owner had recorded negative dipstick test results for glucose in the ferret's urine for 3 consecutive days. During this assessment, blood glucose concentration remained < 200 mg/dL, without any further administration of insulin glargine, for 4 hours (76 hours since the previous insulin glargine injection). At the 4-hour point, the blood glucose concentration increased to > 200 mg/dL. The ferret was discharged from the hospital and returned to the owner's care, who continued to use daily dipstick measurements of glucose in the ferret's urine to determine the need for administration of insulin glargine. At last follow-up, nearly 12 months after the initial administration of insulin glargine, the owner reported that the ferret continued to thrive and was receiving 0.5 U of insulin glargine, SC, every 1 to 3 days.
VetScan VS2, Abaxis, Union City, Calif.
VetScan HM5, Abaxis, Union City, Calif.
Hi-Tech Pharmacal Inc, Amityville, NY.
Lantus, Sanofi-aventis US, Bridgewater, NJ.
U-100 insulin syringes (30 gauge, 3/8 inch, 3/10 mL), CVS Pharmacy Inc, Woonsocket, RI.
Clinistix, Bayer Corp, Elkhart, Ind.
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