An updated examination of renal vascular index metrics for assessing renal involvement in feline infectious peritonitis cases

This study aimed to perform a comparative analysis of renal vascular index parameters including renal resistive index (RRI) and pulsatility index (RPI) in the non-invasive diagnosis of renal damage in cats diagnosed with Feline Infectious Peritonitis (FIP). The study group comprised 17 cats diagnosed with FIP and 10 healthy cats as controls for data comparison. Hematological and biochemical assessments were detected the kidney damage in FIP cases. Comprehensive ultrasound recordings of both kidneys were acquired using abdominal ultrasound. Color and pulsed wave Doppler ultrasonographic imaging, along with RRI and RPI values derived from these assessments, as well as comprehensive total renal ultrasonography evaluations, were documented. The mean RRI and RPI values of the right kidney (0.78 ± 0.11 and 2.12 ± 0.36, respectively) and the left kidney (0.77 ± 0.11 and 1.99 ± 0.09, respectively) were significantly higher in cats with FIP compared to the control group (right kidney: 0.54 ± 0.09 and 0.79 ± 0.21, P < 0.001 and P < 0.041, respectively; left kidney: 0.55 ± 0.10 and 0.80 ± 0.23, P < 0.001 and P < 0.036, respectively). Additionally, ROC analysis also determined the sensitivity and specificity of RRI and RPI (94%, 50% and 100%, 66%) at optimal cut-off points (RRI: 0.58 and RPI: 0.63). These findings reported in the present study is important as it is the first report of vascular index parameters in cats with FIP. These findings suggest that RRI and RPI may represent valuable non-invasive hemodynamic biomarkers for evaluating renal involvement and monitoring the progression of kidney damage associated with FIP.