Epidemiology of Mitral Regurgitation in Maltese

Mitral regurgitation (MR) is a common cardiac disease in the dog. It is more frequently diagnosed in small dogs than large ones. We investigated the epidemiology of MR in Maltese dogs, which was one of the most popular breeds in Japan. The prevalence of MR was defined in 460 (male : 230, female : 230) cases of Maltese dogs. MR was diagnosed by radiography and/or2-D echocardiography. 23.5% of all cases were diagnosed on ausculation to have a systolic regurgitant cardiac murmur. MR was diagnosed in 97% of cases which had systolic regurgitant cardiac murmur. The remaining 3% of cases had other cardiac diseases causing systolic regurgitant murmur. The sex ratio of MR cases was male: female= 1.4 : 1.0. The earliest onset of systolic regurgitant murmur was 5 years old, and the most frequent age of onset was 9 years old. Of the dogs that died, 54% of male and 32% of female dogs died as a result of heart failure.