Glomerulosclerosis in captive cheetahs (Acinonyx jubatus)

The cheetah (Acinonyx jubatus) is an endangered species with low fecundity and premature death in captivity. A previous survey determined that renal failure as a result of glomerulosclerosis was a major cause of death in captive populations. This study characterizes the morphologic, histochemical, and epidemiologic properties of glomerulosclerosis in this population. Kidneys from 87 cheetahs were examined by light microscopy; kidneys from six of those cheetahs were examined by electron and fluorescent microscopy using special stains specific for collagen, glycoproteins, reticulin, and fibrin. Immunohistochemistry for the advanced glycosylation end products (AGEs), pyrraline and pentosidine, also was performed on these cases. Glomerulosclerosis was present to some degree in 82% of the population, and in 30% of cheetahs the sclerosis was moderate to severe. Affected cheetah kidneys had thickened glomerular and tubular basement membranes, culminating in glomerulosclerosis. Thickened basement membranes were positive for collagen, glycoproteins, reticulin, and AGEs. Ultrastructurally, membrane material was homogeneous and fibrillar without electron-dense deposits. This glomerular lesion in cheetahs resembles diabetic glomerulopathy in humans and chronic progressive nephropathy in rats. No cheetahs had lesions of diabetes. However, adrenal cortical hyperplasia was prevalent and highly correlated with glomerulosclerosis in this population. If cheetahs with glomerulosclerosis had hypercorticoidism, then hyperglycemia and glomerular hypertension could lead to progressive AGE and plasma protein accumulations in membrane lesions. As in rats, daily feeding of high-protein diets and lack of genetic variation in the population may further contribute to the high prevalence of glomerulosclerosis in captive cheetahs.