Pulmonic stenosis (PS) is a common congenital heart disease in dogs. It may be associated with an aberrant coronary artery (CA) in brachycephalic breeds. If present, a CA anomaly must be identified before pulmonic valvuloplasty. A 1.7-year-old Boston terrier was referred for a grade V/VI systolic heart murmur and exercise intolerance. Echocardiography revealed combined type B valvular and supravalvular PS; an aberrant CA was also suspected. Non–electrocardiography (ECG)-gated, 160-multislice computed tomographic angiography (CTA) confirmed severe right ventricular wall hypertrophy, a hypoplastic pulmonic valve annulus, and severe supravalvular PS with a marked main pulmonary artery bulge; a single left coronary ostium with an anomalous pre-pulmonic right CA was also identified. Surgical correction with pulmonic valvuloplasty and pulmonary artery patch angioplasty under cardiopulmonary bypass was planned. The patient died intraoperatively due to profound hypotension after weaning from extracorporeal circulation. However, this is the first case report in which type B valvular and supravalvular PS with an aberrant pre-pulmonic right CA was diagnosed by non–ECG-gated, 160-multislice CTA in a Boston terrier, showing a similar level of image quality to ECG-gated CTA. Thus, in PS cases, high-slice CTA may be helpful to determine if CA anomalies are present and to establish a therapeutic plan.