The incidence of mitral valve fisease (MVD) and mitral valve leaflet prolapsed (MVP) in cross breed dogs

Introduction/Purpose: to examine the influence of breed, age, sex, and weight, on MVP and to investigate which of the mitral valve leaflets was most often involved in a large canine population with MVP Material and Methods: Ultrasonographic exams and case records of ninehundred and sixty-four dogs were reviewed retrospectively together with the clinical history and signalment. For each patient echocardiographic data were examined and used for the analysis. Results: Of the ninehundred and sixty-four dogs analyzed, fivehundred and thirty-seven dogs (55,7%) presented with MVP were included in the study. Cross-Breed dogs were the most represented breed (248 medium-sized dogs, 46.2%). MVP was more common among male dogs with advanced age, and there was also a high frequency of MVP among neutered females compared with the same mean age of males. In contrast to humans, where the posterior leaflet is most commonly affected in MVP, in this canine population, prolapse affected only the anterior leaflet of the mitral valve in 48.4 %, only the posterior leaflet was involved in 7.1%, and both leaflets were involved in 48.5%. However, the posterior leaflet on its own tended to be the one predominantly affected together with prolapse in Dachshunds and Shih Tzus. There was no significant correlation between either the degree of prolapse or the affected leaflet and the degree of heart failure as described by the International Small Animal Cardiac Health Council class (ISACHC), mitral annulus diameter, mitral regurgitation grade. Discussion/Conclusions: This study provides evidence of the predisposition of medium-sized Cross-breed dogs to MVP, and highlights the differences in the anatomical leaflet predominantly affected in MVP in dogs compared to humans. Moreover the results obtained in the study permit to "suggest" that the susceptibility for the mitral valve disease is not exclusive of some specific breeds (CKCSpaniel, Dackshunds) since Cross-breed dogs very often present with this disease. In addition our findings suggest that the particular leaflet involved did not affect the severity of the pathological process.