Background: Myxomatous mitral valve disease (MMVD) is the commonest canine heart disease. Red blood cell glycocalyx (RBCGlx) depth is a novel measure of endothelial glycocalyx depth. RBCGlx damage has been demonstrated in dogs with stage B2 MMVD; however, RBCGlx depth is also reduced in some dogs in stage B1. Glycocalyx damage is also associated with proteinuria in people. Hypothesis/objective: Reduced RBCGlx depth predicts progression to stage B2 and is associated with proteinuria. Animals: Client-owned dogs with MMVD (Group 1: 35 dogs, examined twice, stage B1 at baseline; Group 2: 47 dogs undergoing urinalysis).
Methods: Observational longitudinal study. Diagnosis and staging of MMVD was based on the ACVIM consensus statement. RBCGlx was measured on blood smears stained with lectins and octadecyl rhodamine. In Group 1, logistic regression was used to predict MMVD stage at the six-month timepoint. In Group 2, proteinuria was measured at a single timepoint using urine protein-to-creatinine ratio (UPC). A nonlinear regression model was used to assess associations between UPC and RBCGlx depth.
Results: In Group 1, baseline RBCGlx was significantly associated with MMVD stage (B1vsB2) at the six-month timepoint (odds ratio = 0.39 (95% CI = 0.21 – 0.73), P = 0.0035). In Group 2, an exponential decay of UPC with increasing RBCGLx was seen (residual standard error = 0.192). Conclusions and clinical importance: In stage B1 MMVD, RBCGlx damage predicts progression to stage B2, representing a possible prognostic factor. The association between RBCGlx damage and UPC suggests a pathophysiological role for Glx damage in cardiovascular-renal-axis disorders.
