Update on Iohexol Excretion for the Evaluation of Renal Function in The Green Iguana (Iguana iguana)
American Association of Zoo Veterinarians Conference 2005
Stephen J. Hernandez-Divers1, BVetMed, DZooMed, MRCVS, DACZM; Scott J. Stahl2, DVM, DABVP (Avian); Nancy Stedman3, DVM, DACVP; Sonia M. Hernandez-Divers1, DVM, DACZM; Juergen Schumacher4, DrMedVet, DACZM; Christopher S. Hanley1,6, DVM; Heather G. Wilson1, DVM, DABVP (Avian); Wilson K. Rumbeiha5, BVM, PhD, DABVT
1Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, GA, USA; 2Stahl Exotic Animal Veterinary Services, Vienna, VA, USA; 3Department of Veterinary Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA; 4Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA; 5Diagnostic Center for Population and Animal Health, Michigan State University, East Lansing, MI, USA; 6Special Species Service, Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA
Abstract
In a recent paper, plasma biochemistry, iohexol clearance (to determine glomerular filtration rate), and endoscopic renal evaluation with biopsy were performed in 23 clinically healthy 2-year-old green iguanas (Iguana iguana).1 Following the IV injection of 75 mg/kg iohexol into the caudal (ventral coccygeal or tail) vein, serial blood collections were performed over 32 h. Iohexol assays by high-performance liquid chromatography produced plasma iohexol clearance graphs for each lizard. A three-compartment model was used to fit area-under-the-curve values and obtain the glomerular filtration rate using regression analysis. The mean glomerular filtration rate (±SD) was 16.56±3.90 ml/kg/h, with a 95% confidence interval of 14.78–18.34 ml/kg/h. Bilateral endoscopic renal evaluation and biopsy provided tissue samples of excellent diagnostic quality, that correlated with tissue harvested at necropsy and evaluated histologically. None of the 23 animals demonstrated any adverse effects of iohexol clearance or endoscopy.
A prospective clinical study of five iguanas presented with suspected renal disease was undertaken. These animals were similarly evaluated using plasma biochemistry, iohexol clearance and endoscopic renal evaluation. In all cases, GFR was significantly reduced and ranged from 2–12 ml/kg/h. Renal disease was also confirmed histologically by endoscopic renal biopsy and/or necropsy.
Iohexol assays are commercially available through the Diagnostic Center for Population and Animal Health, Michigan State University, East Lansing, MI, USA, and have proven practical for the determination of renal function in the green iguana. Recommended diagnostics for the evaluation of renal function and disease in the green iguana include plasma biochemical profiles, iohexol clearance, endoscopic examination, and renal biopsy.
Literature Cited
1. Hernandez-Divers S.J., S.J. Stahl, N.L. Stedman, S.M. Hernandez-Divers, J. Schumacher J, C.S. Hanley, G.H. Wilson, A.N. Vidyashankar, Y. Zhao and W.K. Rumbeiha. 2005. Renal evaluation in the green iguana (Iguana iguana): Assessment of plasma biochemistry, glomerular filtration rate, and endoscopic biopsy. J. Zoo. Wildl. Med. (In press).