Establishing Renal Function Parameters and Pathology in Free-Ranging and Stranded California Sea Lions (Zalophus californianus)
Michelle R. Rivard1*+; Margaret Martinez1; Cara L. Field1; Katherine Prager2; Rachel Cianciolo3; Jessica A. Hokamp3; Pádraig Duignan1
Abstract
California sea lions (CSLs) are rehabilitated after stranding along the Eastern Pacific coastline and are commonly managed in zoos and aquaria.1 Urinary system diseases such as leptospirosis, urogenital neoplasia, nephrolithiasis and amyloidosis have been described in rehabilitating and managed CSLs, and are diagnosed using serum biochemistry, ultrasonography, and postmortem histology.2–6 Changes in serum biochemistry can be subtle and difficult to distinguish between renal and extra-renal etiologies.7–9 Urinary diagnostic tests can be non-invasive, cost-effective and sensitive in detecting subtle differences in renal function, but are infrequently used because reference ranges in CSLs have not been established.10
The first objective is to establish renal function reference ranges for CSLs using readily available diagnostic tests including urinalysis, urine sediment cytology, and urine protein to creatine ratio (UPC). The second objective is to characterize urine protein profiles using SDS-PAGE gel electrophoresis and serum protein electrophoresis (SPE). The final objective is to describe ultrasonographic, gross, histologic, and ultrastructural characteristics of kidneys in CSLs and correlate with clinicopathologic findings.
A pilot study was performed utilizing two control CSLs and two CSLs with subclinical and clinical renal disease. CSLs with renal disease were proteinuric and UPC was elevated in the CSL with clinical renal disease. CSLs with renal disease had urine protein profiles indicative of tubular and glomerular injury which corresponded to histologic and ultrastructural changes. This pilot data indicates renal function parameters including urinalysis, UPC, SDS-PAGE gel electrophoresis, and SPE are potential diagnostic tools for detection and help direct intervention in CSLs with renal disease.
Acknowledgements
The authors thank Carlos Rios, Jesierose Poblacion, Barbie Halaska and Jaclyn Isbell for assistance with sample collection and analysis, as well as the volunteers at The Marine Mammal Center for their invaluable contributions to this project and their efforts in pinniped rehabilitation and conservation. In addition, the authors thank the many donors who made this research possible.
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