Biomarkers of Kidney Disease in Horses: A Review of the Current Literature

Abstract

Creatinine only allows detection of kidney disease when 60 to 75% of the glomerular function is lost and is therefore not an ideal marker of disease. Additional biomarkers could be beneficial to assess kidney function and disease. The objectives are to describe new equine kidney biomarkers. This systematic review assesses the available literature, including the validation process and reference values, following which the authors suggest recommendations for clinical use. SDMA may have some potential as equine kidney biomarker, but there is currently a lack of evidence that SDMA offers any advantage compared to creatinine in detecting Acute Kidney Injury (AKI). Cystatin C and podocin show potential as biomarkers for kidney disease (including detecting AKI earlier than creatinine) and should be studied further. NGAL has potential as a biomarker of kidney disease (including detecting AKI earlier than creatinine), and potential as an inflammatory marker. Literature on MMP-9 does not allow for conclusive statements about its potential as a biomarker for kidney disease. The future may show that NAG has potential. For all biomarkers, at this stage, available scientific information is limited or too scarce to support clinical use, and only SDMA can be measured for clinical purposes. In conclusion, there are multiple new biomarkers with the potential to diagnose kidney problems. However, there are only a few studies available and more data is needed before these biomarkers can be applied and recommended in our daily practice.

Do post‐surgical multiresistant urinary infections occur in horses? Case of unilateral pyelonephritis caused by extended‐spectrum beta‐lactamase‐producing bacteria as a complication of cystotomy

“…Symmetric dimethylarginine (SDMA) has been recently proposed as an alternative to creatinine and urea, reported to increase with an average of 40% loss of kidney function in small animals (Relford et al., 2016). Moreover, it was shown to be significantly associated with renal disease in horses (Siwinska et al., 2020), however, until now the evidence that it can detect renal disease earlier than creatinine in horses has not been convincing (Siwinska et al., 2020; van Galen et al., 2022). The fact that SDMA was within normal ranges at last follow‐up in this horse (5 years after cystotomy) in the face of chronic ultrasonographic changes suggests that there is either enough functionality in both kidneys (with less than 40% loss of total renal function), or that SDMA increases in horses only after a larger glomerular filtration rate loss than reported in small animals.…”