Vol. 10, Issue 10, Part D (2025)

Renal dysfunction in dogs, encompassing both acute kidney injury (AKI) and chronic kidney disease (CKD), poses diagnostic challenges due to limitations in conventional biomarkers like serum creatinine and blood urea nitrogen (BUN). This study evaluated the diagnostic utility of serum and urinary cystatin C (Cys-C) in differentiating renal dysfunction stages in dogs. Thirty-seven dogs were enrolled, including six healthy controls, six with AKI, and twenty-five with CKD stratified by IRIS staging. Serum and urinary Cys-C concentrations were significantly elevated in dogs with renal dysfunction compared to controls, with progressive increases observed across CKD stages. Notably, Cys-C levels were less influenced by age, sex, or muscle mass, enhancing its reliability as a biomarker. The findings support Cys-C as a sensitive and early indicator of renal impairment, with potential to improve diagnostic accuracy and staging in canine nephrology. Incorporation of Cys-C into routine diagnostic panels may facilitate timely intervention and better clinical outcomes.