Background: Ultrasonography is a preferred diagnostic tool for renal disease in clinical practice. Kidney size is a commonly used morphological parameter in renal assessment; however, it lacks sensitivity for early disease detection. Cortical parameters, particularly cortical thickness, correlate more strongly with early renal disease, as the cortex plays a key role in filtration and is highly vulnerable to injury. Rabbits, widely kept as pets, have distinct renal anatomy and are prone to kidney diseases, making them a relevant model for renal studies. Previous studies have shown that ultrasonography can effectively measure kidney size in rabbits, correlating with body weight. Objectives: This study aimed to establish a normative ratio of renal cortical thickness to the internal diameter of the abdominal aorta in healthy rabbits. Methods: Sixty healthy adult male mixed-breed rabbits underwent ultrasonographic evaluation. Renal cortical thickness and abdominal aortic diameter were measured, ensuring that only rabbits without clinical or ultrasonographic signs of kidney disease were included. Results: Pearson correlation analysis revealed a positive correlation between renal cortical thickness, aortic diameter and body weight. However, the ratio of renal cortical thickness to aortic diameter remained independent of body weight. Conclusions: This study established a normative reference range for renal cortical thickness relative to aortic diameter in rabbits, providing a novel diagnostic parameter for renal assessment. The confidence intervals for the ratio were 0.82 (0.77–0.87) to 1.35 (1.30–1.40) for the left kidney and 0.79 (0.74–0.84) to 1.33 (1.27–1.38) for the right kidney, marking the first report of this method in the literature.

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