Renal Resistive Index as A Potential Indicator of Acute Kidney Injury in Horses.

The research tries to identify if Renal Resistive Index (RRI) can help detect acute kidney injury (AKI) in horses. However, the study suggests that it may not be an effective diagnostic tool due to inconsistencies in RRI values in horses compared to other species, and its complex application in non-cooperative animals.

Objective and Methodology of the Study

• The purpose of the study was to find out if the Renal Resistive Index (RRI) can serve as a diagnostic tool for acute kidney injury (AKI) in horses, and to compare these RRI values with those of healthy horses. In addition, the study sought to examine the impact of potentially nephrotoxic agents on the RRI values.
• The study involved 71 horses divided into three groups – 30 healthy, 11 with AKI and 30 at risk for AKI (10 horses with colic, 10 receiving gentamicin, and 10 receiving NSAIDs).
• For the assessment of AKI, a kidney ultrasonography examination was conducted using pulsed-wave Doppler, and RRI values were observed in intrarenal arteries of all participating horses.

Results and Findings

• The results showed only the right kidney displayed differing RRI values across the groups. The horses with AKI exhibited significantly higher RRI values compared to the healthy ones.
• However, there was no effect of potentially nephrotoxic agents on horse’s RRI value, contradicting an expected result. This means even horses at risk of AKI did not show higher RRI.
• Interestingly, the RRI values in horses were found to be lower than in other species. The increase in RRI values among horses experiencing AKI was also noticeable in just one kidney, and these values did not reach the levels found in other species.

Implications and Conclusion

• The increase in this parameter in horses with AKI, affecting only one kidney, and the lower RRI values than other species, suggests that RRI might not be a reliable indicator for AKI diagnosis in horses.
• Moreover, the practical use of this method in non-cooperating animals remains a challenge, indicating this particular diagnostic approach – RRI Doppler ultrasonography of blood flow in intrarenal arteries – may not be useful in diagnosing AKI in horses in veterinary practice.