Renal Interstitial Lipid Accumulation in Cats with Chronic Kidney Disease

Chronic kidney disease (CKD) is a common progressive condition described in dogs and cats, involving several non-specific morphological and histological lesions. Recently, renal interstitial lipid accumulation was reported in cats with CKD; however, to date, little is known about this condition and its pathogenesis. The aim of this study was to investigate the occurrence and to characterize renal interstitial lipid deposits in dogs and cats. A total of 49 animals (27 cats and 22 dogs) with CKD were included in the study. Interstitial lipid accumulation was found exclusively in cats, affecting both males and females. In 55.6% of the cases, the extent of the lesion was not equally distributed in right and left kidneys. The lesion was always found in the cortical region, associated with an inflammatory reaction. Lipid macrovacuoles were also observed in the tubular epithelium, as well as in areas of tubulorrhexis. The amount of lipid deposited was variable, being more extensive in older animals. Data from this study suggest that interstitial lipid accumulation may be related to tubular lipidosis (typical of feline kidneys) associated with epithelial degeneration and lysis, and to tubular basement membrane fragmentation. Extended studies on this condition are necessary, as it appears to be involved in the progression of CKD and may, therefore, have repercussion in the clinical management of the disease and in the development of new approaches to delay its advance.