Ratio of Urine Levels of Uric Acid to Creatinine as an Aid in Diagnosis of Urate Stones in Bottlenose Dolphins
Thomas H. Reidarson; Jim McBain
Antemortem diagnosis of urate nephrolithiasis in cetaceans is difficult.
Since urate stones account for the majority of renal calculi, the discovery of radiolucent
hyperechoic stones certainly raises one's index of suspicion; however it is by no means
pathognomonic. We examine the ratio of urine uric acid to creatinine in fasted cetaceans to aid
in diagnosis and treatment of urate stones.
In one confirmed and another suspected case of urate nephrolithiasis in two
bottlenose dolphins, the uric acid to creatinine ratios were 0.42 and 0.14, which is 8 and 2
times greater than normal. Our normal ratios were determined from eight bottlenose dolphins
whose urine was collected voluntarily before the first feeding in the morning and after
receiving three, five, or greater than fifteen pounds of fish. The ratios between the groups
were strikingly different. The fasting group was 0.07 (S.D. = 0.01), while the three, five and
greater than 1 5 pound groups were 0. 20 (S. D. = 0. 1 3), 0.6 6 (S. D. = 0.26), and 1.39 (S.D.
= 0.59) respectively. These data indicate that urine collected from fasting animals produced the
most reliable ratios and are significantly lower than two clinical cases of urate