abstract
Clinical serum biochemistries, predicted glomerular filtration rate1 and nuclear scintigraphy2 were used to identify ultrasound-based predictors of renal health in bottlenose dolphins. Seven animals were selected for the study and categorized into the following three renal ultrasound descriptions: 1) 0-5 renal calculi with no visualized collecting duct (three animals), 2) > 5 calculi with no visualized collecting duct (2 animals), and 3) > 5 calculi with a visualized dilated collecting duct (2 animals). Renal scintigraphy utilizing Technetium-99m mercaptoacetyltriglycine was performed on all animals to evaluate renal function. Even distribution of radiotracer in both kidneys was considered normal, which was found in all three controls. The two cases with > 5 calculi but no visible collecting duct had a moderate reduction in function (mean of 22% difference between the kidneys) and the two cases with one dilated collecting duct had a severe reduction in function (mean of 70% difference between kidneys). Ureteral obstruction was suspected in both cases and confirmed by CT in one case with intravenous pyelogram. Although the sample size was small, we found that dolphins with > 5 calculi and a dilated collecting duct were significantly (P < 0.0001) more likely to have higher BUN (> 60 mg/dl), higher creatinine (> 2.3 mg/dl), lower predicted GFR (< 120ml/min/2.78m2) and reduced renal function compared to animals without a visualized collecting duct, regardless of the total number of renal calculi present. If a dolphin has ultrasound evidence of renal calculi, a dilated collecting duct, and clinical blood values outlined above, ureteral obstruction should be a primary rule-out.
acknowledgments
The authors thank the SSC-SD Biosciences Division for their support of this project at all levels. Dr. Sam Ridgway, CPT Nathan Daughenbaugh, and Ms. Veronica Cendejas provided intellectual and clinical support. The Army veterinary technical staff and SSC-SD training staff facilitated animal examination, treatment and transport. Ms. Risa Daniels assisted with data collection and analysis. Ms. Melissa Dolan managed our loan agreement and contract support. We also thank the Office of Naval Research and the SSC-SD In-house Laboratory Independent Research for enabling this project through FY07 & FY08 funding.
References
1. Venn-Watson S, Smith C, Dold C, Ridgway S. Use of a serum-based glomerular filtration rate prediction equation to assess renal function by age, sex, fasting, and health status in bottlenose dolphins (Tursiops truncatus). Mar Mamm Sci (Online Early Articles). doi:10.1111/j.1748-7692.2007.00162.x.
2. Haufe S, Riedmuller K, Haberkorn U. Nuclear medicine procedures for the diagnosis of acute and chronic renal failure. Nephron Clin Pract 2006; 103 (2): 77-84.