2016 ACVIM Forum Research Abstract Program

PCr/ATP ratio would appear to be a measure of cardiac energetics early in the remodelling phase of volume overload MR and allows for the linear measure of the same dog over time to determine disease progression. MRS may provide a useful tool in the evaluation of drug therapy on the cardiac energetics of MR in dogs. Corin is expressed by cardiomyocytes and converts pro-natriuretic peptides to their mature forms, which play a key role in fluid homeostasis and cardiac remodelling. In mice and human with failing hearts, myocardial corin protein levels have been reported to be increased, however without a concomitant increase in corin activity. These findings can partly explain the clear paradox in congestive heart failure (CHF) in that the natriuretic peptides are elevated, yet the body is fluid retaining (ultimately resulting in CHF). Interestingly in the Cavalier King Charles Spaniel, 2 loci associated with development of myxomatous mitral valve disease (MMVD) have been identified. Corin is on one of these loci on the latest dog assembly. This further raises the question whether deficiencies in myocardial corin expression or activity could be a mechanism explaining the progression of heart disease and CHF in dogs as well. The purpose of this study therefore was to characterize the immunohistochemical expression of corin in myocardial tissue in normal dogs and in dogs with severe MMVD.