Early renal changes in non-azotemic geriatric dogs detected by clinical biomarkers and ultrasonography.

This study evaluated renal health in non-azotemic geriatric dogs using routine biomarkers, including the urinary protein-to-creatinine ratio (UPC), urinalysis, fractional excretion of chloride, urinary gamma-glutamyl transferase (uGGT), and urinary alkaline phosphatase (uALP), aiming to identify early indicators of renal injury. These biomarkers were compared with structural changes observed via renal ultrasonography. A total of 84 dogs were enrolled and divided into two groups: young (n = 10; 1-4 years) and geriatric (n = 74; 7-17 years). All dogs underwent complete blood counts, serum biochemistry (creatinine, urea, alkaline phosphatase, alanine aminotransferase, sodium, potassium), and urinary analyses (urinary creatinine, chloride, UPC, uGGT, uALP), along with urinalysis. Renal ultrasonography was performed in dogs with abnormal UPC values. Statistically significant differences were found in UPC and the uGGT/urinary creatinine ratio (p < 0.05). A notable proportion of non-azotemic geriatric dogs showed proteinuria (UPC > 0.5). In these cases, ultrasonography revealed alterations in renal echogenicity-ranging from preserved to mild or marked changes-as well as varying degrees of corticomedullary differentiation and loss of renal architecture. The integration of accessible, low-cost laboratory tests with ultrasonographic assessment offers a more comprehensive evaluation of renal function and morphology, highlighting the importance of early detection for effective management and improved quality of life in aging dogs. As this was a cross-sectional study, evaluation was limited to a single time point; longitudinal follow-up would be valuable to clarify disease progression, especially in borderline or mildly proteinuric dogs.