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 f ailure as a result of glomerulosclerosis was a major cause of death in capt ive populations. This study characterizes the morphologic, histochemical, a nd epidemiologic properties of glomerulosclerosis in this population. Kidne ys from 87 cheetahs were examined by light microscopy; kidneys from six of those cheetahs were examined by electron and fluorescent microscopy using s pecial stains specific for collagen, glycoproteins, reticulin, and fibrin. Immunohistochemistry for the advanced glycosylation end products (AGEs), py rraline and pentosidine, also was performed on these cases. Glomerulosclero sis was present to some degree in 82% of the population, and in 30% of chee tahs the sclerosis was moderate to severe. Affected cheetah kidneys had thi ckened glomerular and tubular basement membranes, culminating in glomerulos clerosis. Thickened basement membranes were positive for collagen, glycopro teins, reticulin, and AGEs. Ultrastructurally, membrane material was homoge neous and fibrillar without electron-dense deposits. This glomerular lesion in cheetahs resembles diabetic glomerulopathy in humans and chronic progre ssive nephropathy in rats. No cheetahs had lesions of diabetes. However, ad renal cortical hyperplasia was prevalent and highly correlated with glomeru losclerosis in this population. If cheetahs with glomerulosclerosis had hyp ercorticoidism, then hyperglycemia and glomerular hypertension could lead t o 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 glomerul osclerosis in captive cheetahs.