Frequency of histologic lesions in the kidneys of cats without kidney disease

Abstract

Objectives In humans, renal aging is associated with an increased frequency of glomerulosclerosis, interstitial fibrosis, inflammation and tubular atrophy. The purpose of this study was to describe the frequency of renal histopathologic lesions in cats without kidney disease. Methods A cross-sectional study of archival kidney tissue from 74 cats without kidney disease (serum creatinine <1.6 mg/dl; urine specific gravity >1.035) was carried out: 0–4 years (young, n = 18); 5–9 years (mature, n = 16); 10–14 years (senior, n = 34), 15+ years (geriatric, n = 6). Glomerulosclerosis, tubular atrophy, interstitial inflammation and fibrosis, and the presence or absence of lipid in the interstitium and tubules were scored by a pathologist masked to clinical data. Statistical analyses were performed as appropriate. Results Geriatric cats had significantly more glomerulosclerosis than mature ( P = 0.01) and young cats ( P = 0.004). Senior cats had significantly more glomerulosclerosis than young cats ( P = 0.006). Glomerulosclerosis was weakly positively correlated with age ( r = 0.48; P <0.0001). Geriatric cats had significantly more tubular atrophy than mature ( P = 0.02) and young cats ( P <0.0001). Senior cats had significantly more tubular atrophy than young cats ( P <0.0001). Geriatric cats had significantly more inflammation than senior cats ( P = 0.02), mature cats ( P = 0.01) and young cats ( P <0.0001). Senior cats had significantly more inflammation than young cats ( P = 0.004). Geriatric and senior cats had significantly more fibrosis than young cats ( P = 0.01 and P = 0.04, respectively). Frequency of tubular lipid increased with age (young: 28%; mature: 56%; senior: 79%; geriatric: 100%) as did the frequency of interstitial lipid (young: 22%, mature: 56%, senior: 85%, geriatric: 100%). Conclusions and relevance Evidence of renal aging exists in cats. These changes imply that the aging kidney may be more susceptible to injury and impaired healing.

Feline Morbillivirus: Clinical Relevance of a Widespread Endemic Viral Infection of Cats

“…When tubular injury involves the basement membrane (tubulorrhexis), inflammation spreads to the interstitium, and focal TIN occurs [65]. Feline tubular cells typically accumulate lipids in the cytoplasm, and leakage of lipids into the interstitium in the case of tubulorrhexis enhances the inflammatory response [66]. Interestingly, a few weeks after experimental infection with FeMV-GT2, multifocal chronic TIN was observed in some cats, similar to what had been seen in feline experimental models of renal ischaemia [35,66].…”

“…Feline tubular cells typically accumulate lipids in the cytoplasm, and leakage of lipids into the interstitium in the case of tubulorrhexis enhances the inflammatory response [66]. Interestingly, a few weeks after experimental infection with FeMV-GT2, multifocal chronic TIN was observed in some cats, similar to what had been seen in feline experimental models of renal ischaemia [35,66]. Indeed, AKI-to-CKD transition is usually triggered by hypoxia regardless of the cause of AKI [65].…”