Evaluation of serum myeloperoxidase concentration in dogs with heart failure due to chronic mitral valvular insufficiency.

Myeloperoxidase (MPO) is a leukocyte-derived enzyme involved in the process of heart failure and is found to have good diagnostic and prognostic values in humans with chronic heart failure. This study evaluated the relationship between serum MPO levels and the severity of heart failure (HF) due to chronic mitral valvular insufficiency (CMVI) in dogs. Eighty-two client-owned dogs consisting of 69 dogs with different stages of HF due to CMVI and 13 age-matched healthy dogs were enrolled in this study. Serum MPO concentrations in the healthy and CMVI groups were determined by enzyme-linked immunosorbent assay (ELISA) using a canine-specific monoclonal anti-MPO antibody. Serum MPO concentrations were 273.3 ± 179.6 ng/L in the controls, 140.8 ± 114.1 ng/L in the International Small Animal Cardiac Health Council (ISACHC) I group, 109.0 ± 85.2 ng/L in the ISACHC II group, and 106.0 ± 42.3 ng/L in the ISACHC III group. Close negative correlation to serum MPO concentration was found in the severity of heart failure (ISACHC stage). Although this study found a modest relationship between serum MPO levels and the severity of HF due to CMVI in dogs, it also suggested that serum MPO levels decreased as the severity of HF increased.