Sixteenanimalsaffectedin2outbreaksofpetfood–associatedrenalfailure(2dogsin;10catsand4dogsin)wereevaluatedforhistopathologic,toxicologic,andclinicopathologicchanges.All16animalshadclinicalandlaboratoryevidenceofuremia,includinganorexia,vomiting,lethargy,polyuria,azotemia,andhyper-phosphatemia.Wheremeasured,serumhepaticenzymeconcentrationswerenormalinanimalsfrombothoutbreaks.Allanimalsdiedorwereeuthanizedbecauseofsevereuremia.Distaltubularlesionswerepresentinall16animals,anduniquepolarizablecrystalswithstria-tionswerepresentindistaltubulesorcollectingductsinallanimals.Theproximaltubuleswerelargelyunaffected.Crystalsandhistologicappearancewereidenticalinbothoutbreaks.Achronicpatternofhistologicchange,characterizedbyinterstitialfibrosisandin-flammation,wasobservedinsomeaffectedani-mals.Melamineandcyanuricacidwerepresentinrenaltissuefrombothoutbreaks.Theseresultsindicatethatthepetfood–associatedrenalfailureoutbreaksinandshareidenticalclinical,histologic,andtoxicologicfindings,providing