Resistivity and Pulsatility Indexes Renal Values Do Not Differ When Obtained from Abdominal or Transrectal Approaches in Healthy Horses

Early detection of renal deficient function is imperative for the success of treatments and determining prognosis. In horses, a renal ultrasound can be performed through the abdominal wall (TA) or transrectally (TR), being an important tool for the evaluation of the kidneys. Besides renal morphology, resistivity (RI) and pulsatility indexes (PI) may be early tools to detect renal injury as they reflect arterial compliance. Twenty-nine healthy adult horses were sonographically evaluated by TA and TR approaches, measuring RI and PI on both kidneys. The mean values from the TA for RI and PI in the right kidney were, respectively, 0.577 ± 0.072 and 0.950 ± 0.182, and 0.553 ± 0.077 and 0.884 ± 0.163 in the left kidney. As for the TR, the mean values for RI and PI in the right kidney were 0.543 ± 0.096 and 0.848 ± 0.212, respectively, and 0.551 ± 0.089 and 0.888 ± 0.204 in the left kidney. No differences (two-way ANOVA) were observed between the left and right kidneys [RI (p = .31) and PI (p = .24)] nor between techniques for both RI and PI, being relevant to state that data on the right kidney by the TR technique did not allow a reliable statistical evaluation. Obtaining good quality TR images in larger horses and satisfactory TA images in obese horses were important differences for each examination technique. In conclusion, there were no differences in RI and PI values obtained from abdominal or transrectal approaches.