Retrospective Analysis of Serum Symmetric Dimethylarginine (SDMA) Concentrations in Cheetahs (Acinonyx jubatus) with Kidney Disease
Kidney disease is common among captive cheetahs (Acinonyx jubatus).5,6,8,9 Serum creatinine is the most common measurement to estimate glomerular filtration rate (GFR), but it is a crude estimate which only increases after significant kidney damage and is affected by extrarenal factors. Symmetric dimethylarginine (SDMA) is a renal biomarker in humans, dogs, and cats, which correlates with GFR and appears to be an earlier, more reliable, and more specific biomarker for kidney disease than creatinine.1-4,7 In dogs, SDMA increased at 49% GFR reduction (versus 75% for creatinine) and 9.8 mo earlier than creatinine.2 In a similar study in cats, SDMA increased 17 mo earlier than creatinine.3 Ninety-two banked serum samples from 11 cheetahs housed at the Oklahoma City Zoo from 1992–2012 were retrospectively analyzed. Histopathology results were available for 10/11 cheetahs and all 10 had histologic renal lesions. General categories of renal lesions included glomerulosclerosis, amyloidosis, inflammatory, and oxalate nephrosis. SDMA immunoassay (IDEXX SDMA™ Test) and liquid chromatography-mass spectrometry were measured for validation and compared with creatinine to assess for correlation. Serum creatinine concentrations were determined by enzymatic colorimetric methods and compared with historical measurements. SDMA immunoassay was validated and correlated well with serum creatinine. These data support that SDMA could be a promising renal biomarker in cheetahs. Further research is warranted to investigate whether SDMA might be an earlier indicator of kidney disease in cheetahs than creatinine and whether this assay can be extended to other nondomestic carnivores.
The authors would like to thank IDEXX Laboratories for donation of time and resources in support of this project as well as Dr. Jane Robertson, Jay McCarty, and Rachel Murphy for assistance with logistics and Dr. Donald McCrann for assistance with statistics. The authors are grateful to the veterinary technicians at the Oklahoma City Zoo for their maintenance of the serum bank and for their time and effort in organizing the samples for this study.
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