High prevalence of renal amyloidosis in cats in an overcrowded colony.

Multiple cats in an overcrowded colony died of acute kidney injury with renal amyloidosis. To investigate the etiology of these deaths, we performed histological analysis of the kidneys of 27 colony cats and 29 noncolony cats (8 with acute kidney injury, 9 with chronic kidney disease, and 12 nonazotemic). Congo red-positive amyloid deposition was observed prominently in the glomeruli and cortical and medullary interstitium and was identified as AA amyloid using permanence. The prevalence and severity of renal amyloidosis were significantly higher in colony cats than in noncolony cats. Feline immunodeficiency virus showed no association with feline leukemia virus infection. Based on our results, adverse environmental conditions may accelerate the incidence of feline renal amyloidosis.