Renal Resistive Index as A Potential Indicator of Acute Kidney Injury in Horses.
Authors: Siwinska Natalia, Zak Agnieszka, Slowikowska Malwina, Paslawska Urszula
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Renal Resistive Index and Acute Kidney Injury in Horses Polish researchers examined whether renal resistive index (RRI)—a Doppler ultrasound measurement of blood flow resistance in intrarenal arteries—could serve as a reliable diagnostic marker for acute kidney injury in horses, comparing 30 healthy animals against 11 with clinical AKI and 30 at-risk horses (those with colic, receiving gentamicin, or on NSAIDs). Horses diagnosed with AKI showed significantly elevated RRI values in the right kidney compared to healthy controls, suggesting the parameter does respond to kidney pathology; however, these increases were smaller in magnitude than reported in other species and affected only one kidney, limiting diagnostic sensitivity. Notably, potentially nephrotoxic exposures (aminoglycosides and anti-inflammatories) did not produce detectable RRI changes in the at-risk group, indicating the measure lacks predictive value for subclinical injury. Whilst Doppler ultrasonography is accessible in practice, the technical demands of acquiring reliable measurements in uncooperative animals combined with modest and inconsistent changes makes RRI of questionable utility as a standalone diagnostic tool for equine AKI, though it may warrant further investigation as part of a broader ultrasonic assessment rather than as an independent screening method.
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Practical Takeaways
- •Renal resistive index measured via Doppler ultrasound is unlikely to be a clinically useful diagnostic tool for detecting acute kidney injury in horses, particularly in field practice settings with uncooperative animals
- •While RRI does increase in horses with clinical AKI, the effect is subtle (lower than in other species) and asymmetrical (right kidney only), limiting its practical diagnostic value
- •Continue to rely on conventional diagnostic approaches (clinical signs, bloodwork, urinalysis) rather than Doppler ultrasonography for detecting subclinical AKI in at-risk horses receiving gentamicin or NSAIDs
Key Findings
- •Horses with acute kidney injury had significantly higher renal resistive index (RRI) values in the right kidney compared to healthy horses (30 healthy controls)
- •RRI values in horses were lower overall than in other species, and increases were limited to one kidney only
- •Potentially nephrotoxic agents (gentamicin and NSAIDs) in at-risk horses (30 total) did not show significant effects on RRI values
- •Doppler ultrasonography of intrarenal arteries has poor clinical utility as a diagnostic tool for acute kidney injury in horses due to limited applicability in non-cooperating animals