| Summary: | Dilated cardiomyopathy (DCM) is common in pedigree dog breeds including Newfoundlands. The breed predisposition and the familial prevalence within breeds support a genetic basis to the disease. Familial occurrence of DCM has only recently been recognised in man, and echocardiography abnormalities are common in relatives of DCM patients. Echocardiography is the method of choice for confirming the diagnosis of DCM. Echocardiographic/Doppler data are presented from 223 scans from 165 individual Newfoundland dogs. The scans were categorised into six groups based on the clinical presentation, M-mode echocardiography results and the Doppler derived aortic velocity. The Normal group showed no abnormalities (n=86). The DCM (overt or occult) group had a rounded left ventricle and fractional shortening (FS) <22% (n=35). There were two depressed fractional shortening groups, without other abnormalities; one with FS less than 18% (dFS<18%) (n=29) and the other with FS 18-20% (dFS18-20%) (n=24). The left ventricular enlargement (LVE) group was defined as a LV diastolic dimension greater than 55mm (males) or >50 mm (females), without any M-mode evidence of systolic dysfunction (n=8). Dogs with an aortic velocity exceeding 1.7 m/s were defined as showing evidence of subaortic stenosis (SAS group) (n=40). Data from complete echocardiographic/Doppler analysis of the Normal group were assessed for dependence on the gender, age and size of dog (weight or body surface area (BSA)) and the heart rate (mean R-R interval) by linear regression analyses. LV volumes and M-mode measurements were positively correlated with size. Gender was not an important predictor of most echo measurements once data was normalised for BSA. Advancing age was a significant negative predictor of LV volumes and dimensions although influence on wall thickness was not significant. Age also showed a significant influence on diastolic function, assessed by mitral inflow and pulmonary venous flow, similar to changes described in man. The ...
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