Prevalence and diagnostic characteristics of non-clinical mitral regurgitation murmurs in North American Whippets.

OBJECTIVES: To assess the prevalence of functional ejection murmurs and murmurs of mitral regurgitation (MR) due to myxomatous mitral valve disease in healthy whippets; to assess the diagnostic value of auscultation to detect MR; and investigate the relationship between age and presence of echocardiographically documented MR (MRecho ).

ANIMALS: A total of 200 healthy client-owned Whippets, recruited at national shows between 2005 and 2009 were involved in this study.

METHODS: Cross-sectional study. Dogs were examined by auscultation by one examiner and Doppler echocardiography by another, and results were compared. Prevalence of types of murmurs and MRecho were calculated and correlated to age. Accuracy of auscultation to predict MRecho was calculated.

RESULTS: Left-sided systolic heart murmurs were detected in 185/200 (93%) of dogs. Left apical systolic murmurs (Lapex ) were detected in 57/200 (29%) and left basilar systolic murmurs (Lbase ) in 128/200 of the dogs (64%). MRecho was present in 76/200 (38%) dogs. Prevalence MRecho was correlated with age (r = 0.96, p=0.0028). Mitral regurgitation detected by echocardiography was present in 12/78 (15%) of the dogs ≤ 2 years of age and in 59% of the dogs at 7-8 years old. Detection of Lapex predicted MRecho with sensitivity 65%, specificity 94%, positive predictive value 86%, and negative predictive value 81%; and accuracy improved when only dogs with more intense Lapex (grade ≥ 3/6) were considered.

CONCLUSIONS: Systolic murmurs are common in North American Whippets and this breed exhibits a high prevalence of MRecho , which may be documented at a relatively early age. Whippets with non-clinical MRecho may not be identifiable by auscultation alone; echocardiographic examination may be required to exclude a diagnosis of MR. Louder heart murmurs allow more accurate localization in this population.