In 6 female goats, the mean threshold for glucosuria was 159.5 +/- 4.3 mg/dl. During increasing filtered loads of glucose, renal reabsorption of glucose reached maximal capacity, which was not exceeded when plasma glucose concentration was increased further. Measured in 10 female goats, the transport maximum for glucose was 119.1 +/- 9.1 mg of glucose reabsorbed/min. During infusion of glucose, there was a significant (P < 0.05) time-dependent reduction in inulin clearance indicating that IV glucose administration may be inappropriate in goats with compromised renal function.

Aminoglycoside nephrotoxicosis (AGNT) was induced in ewes by daily SC administration of gentamicin. Changes in urinary indices of renal function during the development of AGNT are reported. Measurements from timed, volume-measured urine samples were made on days 0, 7, and 8 and included creatinine clearance, total excretion (TE) rates of electrolytes (Na, K, Cl, P) and urine volume. Measurements from free-catch urine samples (without volume measurement) were made daily and included fractional excretion (FE) rate of electrolytes, urine osmolality, and urine-to-serum osmolality and urine-to-serum creatinine ratios. With the onset of AGNT, FE rates of Na, K, Cl, and P increased many fold above baseline values (200 X, 4 to 5 X, 6 to 9 X, and 70 to 95 X, respectively, on days 7 and 8), indicating decreased tubular reabsorption or increased tubular secretion. The increased FE rates were not representative of increases in total electrolyte excretion rates. The total excretion of Na (TE(Na)) was mildly increased, TE(K) was decreased, TE(Cl) was unchanged, and TE(P) was significantly increased on days 7 and 8. Abnormal urinalysis results, glucosuria, and increased FE(P) preceded appreciable increase in serum creatinine concentration. Other abnormal urinary indices of renal function coincided with or followed the increase in serum creatinine concentration. Urinary indices may help characterize renal function associated with the disease state, but did not provide early indication of AGNT.

Venous access devices connected to jugular vein catheters were implanted SC in 2 groups of 6 White Carneau pigeons (Columba livia). Total parenteral nutrition (TPN), or a control solution (lactated Ringer's solution) was infused as a bolus 4 times daily. Physiologic, hematologic, and biochemical variables were monitored over 5 days. Complications in the TPN-treated pigeons included 8.7% weight loss during the 5-day trial, hyperglycemia for up to 90 minutes after infusion, and glucosuria after infusion. Control pigeons lost 1.3% of their body weight and did not become hyperglycemic or glucosuric after infusion. Hematocrit in both groups of pigeons decreased to a value slightly below published reference values for pigeons. Five pigeons developed venous thrombosis in the proximal part of the cranial vena cava. Results indicated that intermittent administration of TPN is possible in birds; however, further research is required to develop better techniques for administration of TPN solutions. Additionally, it is important to determine, more specifically, the caloric and nutrient requirements of pigeons under stress and receiving TPN.