Echocardiographic measurements in Greyhounds, Whippets and Italian Greyhounds - dogs with a similar conformation but different size

Objective To determine the effect of body size on various echocardiographic measurements in dogs of widely differing size, but identical body conforma tion. Design A randomised echocardiographic study of healthy sighthounds. Animals 60 dogs comprising an equal number (20) of racing Greyhounds, Whipp ets and Italian Greyhounds. Procedure Following sedation with acepromazine and morphine, and acclimatis ation, a thorough echocardiographic examination was performed on each dog u sing standard methods. Results Dimensions measured echocardiographically were highly correlated wi th body size. These data were subsequently examined using analyses of varia nce and regression. Body surface area was the best overall predictor of dim ensional measurements. In comparison to previous studies using dogs of diff ering size and conformation, the spread of values for measurements plotted against body surface area showed substantially narrower ranges. Thus, the r elationship between echocardiographic measurements and body surface area wa s much closer for dogs with an identical somatotype than for dogs of differ ing size and conformation. Commonly used ejection phase indices (fractional shortening, ejection fraction and velocity of circumferential fibre shorte ning) were negatively correlated with body size. In contrast, the thickenin g fraction of the left ventricular posterior wall, another ejection phase i ndex, was independent of body weight and body surface area for all three br eeds and when the data were pooled. Conclusion Taken in consideration with previous work, this study demonstrat es that body conformation and body size both influence canine echocardiogra phic measurements. Commonly used ejection phase indices are significantly a ffected by body size, with larger sighthounds having lower values. A more a ppropriate method of quantitating left ventricular function may be the dete rmination of the thickening fraction of the left ventricular posterior wall .