Urocystitis, pyelonephritis, renal papillary necrosis and chronic tubulointerstitial disease causing chronic renal insufficiency in a Siberian tiger (Panthera tigris altaica): A case report

The present case report describes a case of chronic renal failure characterised by renal medullary fibrosis and renal papillary necrosis in a male Siberian tiger (Panthera tigris altaica). A 12-year-old male Siberian tiger presented with depression, anorexia and weight loss. Blood urea nitrogen (> 50.4 mmol/l) and ammonia (71.7 µmol/l) were increased, suggesting chronic renal failure and uraemia. The tiger died secondary to gastric haemorrhage. At necropsy, the kidneys had yellow lesions in the medulla and renal papillae and petechiae in the cortex. The stomach had multiple mucosal ulcers and haemorrhage. Microscopically, marked renal medullary fibrosis and renal papillary necrosis were observed with tubular atrophy, degeneration, coagulative necrosis, calcification and chronic inflammatory cell infiltration. The renal cortex showed moderate interstitial inflammation. The urinary bladder exhibited epithelial desquamation and submucosal fibrosis. The tiger was diagnosed with chronic renal failure secondary to renal papillary necrosis and medullary fibrosis.