Renal Resistive Index and activity of Renin-angiotensin-aldosterone System Components in Persian Cats With Polycystic Kidney Disease

Background: Polycystic kidney disease (PKD) in Persian cats is a common genetic disorder that accounts for 10% of chronic renal failures. Objectives: This study aimed to assess the effect of PKD progression on renal resistive index (RI), plasma renin activity (PRA), angiotensin II (ANG II), aldosterone levels, and systolic blood pressure in Persian cats. Methods: Fifty Persian cats (25 with PKD and 25 healthy) were included in the present study. First, the blood pressure of each cat was measured, and then their PRA, ANG II, and aldosterone enzymes were evaluated using an ELISA test. Additionally, B-Mode ultrasonography was performed in the PKD group to evaluate and calculate cysts’ diameter and overall volume (OVC). Furthermore, the RI was computed by pulsed-wave Doppler in all cats. Results: There were no significant differences in the systolic blood pressure between healthy and PKD cats (138.84±2.89 vs 140.92±2.35 mm Hg). PRA, aldosterone, and ANG II were significantly higher in the PKD group compared to the healthy group (3.64±0.36 vs 2.26±0.029 ng/mL, P<0.01; 80.45±2.35 vs 30.98±1.75 pg/mL, P<0.0001; and 53.54±3.22 vs 30.08±3.06 pg/mL, P<0.0001, respectively). Statistically significant increases (P<0.0001) were detected in RIs of right and left kidneys in PKD cats (0.72±0.01 and 0.71±0.008, respectively) compared with healthy ones (0.59±0.008 and 0.60±0.008). The statistical analysis showed a strong direct correlation between RI changes and the right or left kidney OVC (P<0.001), showing the correlation between RI increase and renal disease progression. Conclusion: An increase in renin-angiotensin-aldosterone activity and RI in Persian cats diagnosed with PKD can be valuable diagnostic tools for their renal disease progression. However, our results showed that the systemic blood pressure is maintained and stays in its normal range.