This report examined cardiac pathologic findings in bull terriers, particularly familial early-onset myxomatous degeneration of the mitral valve (MVD) with regurgitation. Associated coronary arteriosclerosis and myocardial interstitial fibrosis with congestive heart failure is common, and death results from sudden arrhythmias, pulmonary thromboembolic disease, hypoxemia, and systemic organ failure. Subvalvular left ventricular outflow tract obstruction (LVOTO) is also common in the breed and can cause sudden death. Hearts from deceased bull terriers (n = 27) and control dogs (n = 6) were examined for gross and microscopic disease. Dogs were stratified into 4 groups: bull terriers without clinical cardiac disease, bull terriers with heart murmurs, bull terriers with congestive heart failure or sudden death, or control nonbull terrier shelter dogs without cardiac disease. MVD was identified in group 1 (9 of 11), group 2 (11 of 11), and group 3 (5 of 5) dogs. LVOTO was seen in group 2 (1 of 11) and group 3 (3 of 5) dogs; all dogs with fixed LVOTO had evidence of aortic valve myxomatous degeneration. Aortic valvular pathology was identified in group 1 (5 of 11), group 2 (9 of 11), and group 3 (4 of 5) dogs. In addition, coronary arterial lesions were identified in 25 of 27 bull terriers; arteriosclerosis of the small vessels was a common finding, as were inflammation and fibrosis of the conduction tissue.

Commentary: Bull terriers exhibited significant cardiac pathologic findings in this study. This urges the clinical veterinarian to recognize the familial nature of cardiovascular disease in both symptomatic and asymptomatic bull terriers and warn owners of the potential clinical ramifications, even if disease is not identified on a cardiac workup.

Cardiac valvular and vascular disease in bull terriers. O’Leary A, Wilkie I. VET PATHOL 6:1149-1155, 2009.