Echocardiographic ratio indices in overtly healthy Boxer dogs screened for heart disease.
BACKGROUND
Boxer dogs are routinely screened by echocardiography to exclude congenital and acquired heart disease. Individuals of a given breed may span a large range of body sizes, potentially invalidating linear regression of M-mode measurements against body weight. Echocardiographic ratio indices (ERIs) provide a novel method of characterizing echocardiographic differences between Boxers and other dog breeds.


OBJECTIVE
ERIs obtained from overtly healthy Boxer dogs presented for cardiac screening will be different from ERIs established for normal non-Boxer dogs, and those differences will be unrelated to aortic velocity or systolic blood pressure.


METHODS
Eighty-one Boxers with no outward clinical signs of heart disease were studied.


METHODS
All dogs were examined by 2-dimensional, M-mode, and Doppler echocardiography. M-mode measurements were used to perform ERI calculations, and the indices in Boxers were compared between Boxers with varying severity of arrhythmia and those of normal non-Boxer dogs.


RESULTS
Differences in weight-based ERIs, which reflect increased thickness of the left ventricular free wall (LVW) and interventricular septum (IVS) and smaller aortic size, were found in overtly healthy Boxer dogs compared with normal non-Boxer dogs. ERIs of left atrial and LV cavity size in overtly healthy Boxers were not significantly different from those of non-Boxer dogs.


CONCLUSIONS
Boxer dogs may have an increased relative thickness of the LVW and IVS that is independent of aortic size, aortic velocity, or arterial blood pressure, and this morphology should be taken into consideration when screening Boxers by echocardiography.
Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, North Grafton, MA 01536, USA.
S M
SM
Cunningham
J E
JE
Rush
L M
LM
Freeman
D J
DJ
Brown
C E
CE
Smith
D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis*; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary*; D005260:Female; D006331:Heart Diseases / Q000175:diagnosis / Q000662:veterinary*; D008297:Male