Microribonucleic acids (miRNAs) are short RNA molecules which regulate gene expression. They show a varying expression in many diseases, including heart disease. miRNAs are stable and detectable from blood. Therefore, they are potential biomarkers. Myxomatous mitral valve disease (MMVD) is the most common heart disease in dogs. In the long preclinical phase, progressive degeneration of the mitral valve leads to eccentric left-ventricular and -atrial hypertrophy, eventually succeeded by congestive heart failure and death. We aimed to investigate the expression of miRNAs in blood plasma of dogs in consecutive stages of MMVD.

One hundred-eighty-three miRNAs were quantified from blood plasma using RT-qPCR in 10 dogs passing 3 stages of MMVD (modified CHIEF stage B1, B2, and C2/C3). One-way repeated measures ANOVA and pairwise comparisons using Benjamini-Hochberg-correction showed significant differences (p<0.05) in expression within 3 miRNAs: cfa-miR-92b was downregulated in MMVD stage C2 compared to stage B1 and B2 by the factor of 0.52 and 0.61, respectively. cfa-miR-92a and cfa-miR-1306 were downregulated in MMVD stage C2 compared to stage B1 by the factor of 0.60 and 0.53, respectively. There was no significant difference between any other stages.

The results show that there were miRNAs in canine blood plasma that differed in expression with progressing MMVD. However, the total number of miRNAs varying and the difference between stages were small. To evaluate the role of miRNAs as potential biomarkers, further studies are needed - with a bigger population eventually including more stages of disease and healthy control subjects.

Disclosures

The authors have the following disclosures related to the study described in their abstract: The American Kennel Club, Canine Health Foundation, Inc. (Raleigh, NC, USA) provided a research grant ($24,850) that covered the laboratory consumables used in this study. There was no further financial or other form of support. The authors do not have commercial interests and have not made investments related to the study. The authors' institution does not benefit from the results of the study. There were no gifts, hospitality, or travel support.