Comparison of serum microRNA in healthy horses and horses with moderate to severe mitral valve regurgitation using a commercially available canine cardiac panel.

Background: MicroRNA (miRNA) has previously been used as a biomarker for cardiac disease in humans and dogs, however, studies in horses are not yet available.

Objectives: To determine if adult horses with moderate or severe mitral valve regurgitation have a different serum miRNA expression profile compared to healthy controls.

Study design: Retrospective cross-sectional.

Methods: Serum samples from 77 adult horses with moderate or severe mitral valve regurgitation and 77 healthy control horses were analysed using a commercial cardiac disease-specific miRNA panel previously used in dogs.

Results: The commercial canine cardiac miRNA panel had low discriminatory power as a biomarker for mitral valve regurgitation in adult horses. Sensitivity was 0.58 (95% Cl: 0.47-0.69) and specificity 0.57 (95% Cl: 0.46-0.68).

Main limitations: Clinical data were extracted retrospectively and currently there is no well-established criteria for grading mitral regurgitation in horses; there were few severe mitral regurgitation cases and the pathogenesis of mitral regurgitation was not considered. Controls were not matched by age, breed or sex. An assay developed for use in dogs was used.

Conclusion: Despite strong miRNA conservation across species, the commercially available canine cardiac miRNA panel failed as biomarker for mitral valve regurgitation in adult horses. Further research is needed to determine if an equine specific panel can be developed that performs better as biomarker for cardiac disease in horses.