Limitations and Impacts of the Renal Portal System on the Determination of the Glomerular Filtration Rate Using Contrast-Enhanced Computed Tomography and Plasma Clearance of Iohexol in Bearded Dragons (Pogona vitticeps)
American Association of Zoo Veterinarians Conference 2017
Marjorie Bercier, DVM; Robson F. Giglio, DVM, MSc, PhD; Matthew D. Winter, DVM, DACVR; James F.X. Wellehan, Jr., DVM, MS, PhD, DACZM, DACVM (Virology, Bacteriology/Mycology), DECZM (Herpetology)
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA


Due to unique anatomy, physiology, and interspecific variation, renal disease can be challenging to diagnose and treat in reptiles.4 The glomerular filtration rate (GFR) is an indicator of renal function and has been commonly used in human and veterinary medicine. The plasma clearance of iohexol (PCI) and contrast-enhanced computed tomography (CT) have been used to determine the GFR in healthy and diseased individuals.1-7 This pilot study was initially designed to determine the GFR of bearded dragons (Pogona vitticeps) using contrast-enhanced CT and PCI. Ten bearded dragons were used for this study. Dynamic images of the kidneys were obtained sequentially every 2.5 sec for 2 min after an intravenous injection of iohexola (600 mg/kg) via a catheter placed in the ventral coccygeal vein. Time-attenuation curves were constructed and GFR was obtained using Patlak plot analysis. Individual kidney and global GFR were calculated. Plasma iohexol concentration was measured at three time points (4 h, 8 h, and 12 h after iohexol administration) using high-performance liquid chromatography, and GFR was calculated. The average global GFR was 1.52±0.98 ml/min/kg using contrast-enhanced CT and 0.24±0.06 ml/min/kg using PCI. The correlation between the two methods was poor. The renal portal system, and at times the lymphatic system, could be visualized on CT images and evidently impacted GFR calculations using both techniques. This study highlights the limitations for GFR measurements in bearded dragons and raises questions on the reliability of the ventral coccygeal vein for research purposes such as pharmacokinetic studies.


aOmnipaque, 300 mg/ml, Amersham Health, Princeton, NJ, USA


The authors thank Linda Archer, Robin Bast, Hollie Chiles, and Rachel Henriquez for their assistance with data collection.

Literature Cited

1.  Alexander K, del Castillo JRE, Ybarra N, Morin V, Gauvin D, Authier A, Vinay P, Troncy E. Single-slice dynamic computed tomographic determination of glomerular filtration rate by use of Patlak plot analysis in anesthetized pigs. Am J Vet Res. 2007;68:297–304.

2.  Alexander K, Dunn M, Norman Carmel E, Lavoie JP, del Castillo JRE. Clinical application of Patlak plot CT-GFR in animals with upper urinary tract disease. Vet Radiol Ultrasound. 2010;52:421–427.

3.  Alexander K, Ybarra N, del Castillo JRE, Morin V, Gauvin D, Bichot S, Beauchamp G, Troncy E. Determination of glomerular filtration rate in anesthetized pigs by use of three-phase whole kidney computed tomography and Patlak plot analysis. Am J Vet Res. 2008;69:1455–1462.

4.  Hernandez-Divers SJ, Innis CJ. Renal disease in reptiles: diagnosis and clinical management. In: Mader DJ, ed. Reptile Medicine and Surgery. St. Louis, MO: Elsevier Saunders; 2006:878–892.

5.  Hernandez-Divers SJ, Stahl SJ, Stedman NS, Hernandez-Divers SM, Schumacher J, Hanley CS, Wilson H, Vidyashankar AN, Zhao Y, Rumbeiha WK. Renal evaluation in the healthy green iguana (Iguana iguana): assessment of plasma biochemistry, glomerular filtration rate, and endoscopic biopsy. J Zoo Wildl Med. 2005;36:155–168.

6.  Kennedy A, Innis C, Rumbeiha W. Determination of glomerular filtration rate in juvenile Kemp’s Ridley turtles (Lepidochelys kempii) using iohexol clearance, with preliminary comparison of clinically healthy turtles vs. those with renal disease. J Herpetol Med Surg. 2012;22:25–29.

7.  O’Dell-Anderson KJ, Twardock R, Grimm JB, Grimm KA, Constable PD. Determination of glomerular filtration rate in dogs using contrast-enhanced computed tomography. Vet Radiol Ultrasound. 2006;47:127–135.


Speaker Information
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Marjorie Bercier, DVM
Department of Small Animal Clinical Sciences
College of Veterinary Medicine
University of Florida
Gainesville, FL, USA

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