Analysis of survival among biopsy-determined categories of kidney disease in dogs

Abstract

Background: There are many causes of kidney disease in dogs. The association of the diagnostic category with survival is unknown.

Objective: Determine survival outcomes for biopsy-determined diagnostic categories of kidney disease in dogs.

Animals: Six hundred forty-nine dogs were biopsied for evaluation of kidney disease.

Methods: Retrospective study. Survival information was obtained for dogs whose kidney biopsy was submitted to the International Veterinary Renal Pathology Service between 2008 and 2018. Signalment, serum creatinine (sCr), urine protein : creatinine ratio (UPCR), and serum albumin (sAlb) were reported at the time of biopsy. Cox proportional hazards analysis was performed for the 14 categories with >10 cases having follow-up to determine hazard ratios (HR), using focal segmental glomerulosclerosis (FSGS) as baseline.

Results: The median survival time (MST) for all dogs with follow-up (n = 649) was 608 days (interquartile range [IQR]: 109-1475 days). The most follow-up was obtained for FSGS (n = 138, MST 536 days). Dogs with renal amyloidosis (n = 80) had the shortest survival (MST 76 days, IQR 8-299 days) and, in the multivariate analysis including age, sCr, sAlb, and UPCR, an increased risk of death (HR 1.79 [95% CI: 1.22-2.65], P < .01). Dogs with podocytopathy, membranous glomerulonephritis (MGN), mixed MGN, membranoproliferative GN (MPGN), and mixed MPGN had decreased risk of death. Regardless of category, increasing age, sCr, and UPCR and decreased sAlb were associated with a greater risk of death.

Conclusions: The diagnostic category is associated with survival in dogs with kidney disease. Survival of individual dogs within each category was highly variable.

Keywords: chronic kidney disease; glomerular disease; kidney biopsy; proteinuria.

FIGURE 1

Pathologic classification of diagnostic categories of kidney disease. Classification was largely based on histopathological findings, with subclassification of glomerular categories based on non‐immune complex‐mediated versus ICGN. The juvenile nephropathy category represents lesions suspected to be due to renal maldevelopment or reflux nephropathy., ATN, acute tubular necrosis; C3GN, glomerulonephritis with C3‐dominant deposits; FSGS, focal segmental glomerulosclerosis; GBM, glomerular basement membrane; GN, glomerulonephritis; GP, glomerulopathy; ICGN, immune complex‐mediated glomerulonephritis; MGN, membranous glomerulonephritis; MPGN, membranoproliferative glomerulonephritis. Created by C. Rivera 2024 with BioRender.com.

FIGURE 2

Distribution of all kidney biopsies from dogs submitted to the International Veterinary Renal Pathology Service between 2008 and 2018 based on UPCR categories and primary segment of the kidney affected based on diagnostic category of disease.