Prevalence and Clinical Significance of Heart Murmurs Detected on Cardiac Auscultation in 856 Cats

Abstract

Background: Cardiac auscultation is one of the most important clinical tools to identify patients with a potential heart disease. Although several publications have reported the prevalence of murmurs in cats, little information is available in relation to the exact origin of the blood flow turbulences responsible for these murmurs. The aim of this study was to determine the prevalence and clinical significance of murmurs detected during physical examination in cats.

Methods: Retrospective evaluation of clinical records and echocardiographic examinations performed in cats for investigation of heart murmurs; Results: Records of 856 cats with full clinical information were available for review. The cause of murmur was identified in 93.1% of cases (72.3% with single blood flow turbulence, 26.4% with two, and 1.3% with three identifiable sources of murmur). Systolic anterior motion of the mitral valve (SAM) was the primary cause of murmur in this population (39.2%), followed by dynamic right ventricular outflow tract obstruction (DRVOTO) (32%) and flow murmurs (6.9%). Most cats with a murmur (56.7%) did not present any structural cardiac abnormality.

Conclusions: This study indicates that some heart murmur characteristics (timing, loudness and point of maximal intensity) can potentially predict the presence of an underlying cardiac disease.

Keywords: DRVOTO; SAM; acquired; cardiology; cats; congenital; feline; heart murmur; iatrogenic murmur; innocent.

Figure 1

Histogram showing the prevalence of soft, moderate, loud and palpable heart murmurs in a population of 856 cats referred for diagnostic investigation of their murmur.

Figure 2

Histogram showing the frequency of various origins of blood flow turbulence responsible for the presence of an audible heart murmur in a population of 856 cats. SAM: systolic anterior motion of the mitral valve; DRVOTO: dynamic right ventricular outflow tract obstruction; TR: tricuspid regurgitation; MR: mitral regurgitation; Mid-LVOTO: mid-left ventricular outflow tract obstruction; VSD: ventricular septal defect; DCRV: double-chambered right ventricle; AI: aortic insufficiency; PS: pulmonic stenosis; AS: aortic stenosis; CTS: cor triatriatum sinister; PDA: patent ductus arteriosus; MS: mitral valve stenosis; SAS: sub-aortic stenosis; ASD: atrial septal defect; AV canal: atrioventricular canal defect; Supra AS: supravalvular aortic stenosis; TOF: tetralogy of Fallot; CA to PA fistula: coronary to pulmonary artery fistula.