Auxiliar Professor Faculty of Veterinary Medicine, Lusofona University of Lisbon LISBOA, Lisboa, Portugal
Abstract: Feline kidney disease, including chronic kidney disease (CKD) and acute kidney injury (AKI), is a major concern in veterinary medicine. Despite the availability of diagnostic tools such as serum biomarkers and ultrasound, there is a need for novel, practical, and reliable methods to distinguish between healthy cats and those with renal disease. This study introduces the renal cortical thickness to abdominal aortic diameter ratio (RCA/Ao) as a non-invasive, quantitative ultrasound marker for CKD and AKI in cats. To evaluate the RCA/Ao ratio as a diagnostic marker for renal disease and assess its correlation with serum biomarkers. A total of 105 client-owned cats were enrolled: Healthy (n=50), CKD (n=44) and AKI (n=11). Sagittal ultrasound images of the kidneys and aorta were obtained. Renal cortical thickness was measured at three locations, while aortic diameter was measured at systole, caudal to the left renal artery bifurcation. Serum biomarkers (BUN, phosphorus, creatinine, SDMA) were analyzed. The RCA/Ao ratio was: 1.04±0.32 cm (healthy), 1.90±0.77 cm (CKD) and 1.97±0.85 cm (AKI). A cutoff of ≥1.4 cm had 81.82% sensitivity and 86% specificity for detecting renal disease. This study introduces RCA/Ao as a novel, quantitative, non-invasive diagnostic tool for feline kidney disease. Its simplicity, reproducibility, and strong correlation with renal biomarkers support its inclusion in veterinary diagnostic protocols, aiding early detection and disease management.
