Abstract
Background:
The aorto-left ventricular tunnel (ALVT) is a congenital extracardiac channel that connects the ascending aorta to the left ventricle.
Case Description:
A 2-year-old Shih-tzu dog presented with mild exercise intolerance. Echocardiography revealed an abnormal slit-like tunnel structure connecting the ascending aorta to the left ventricle, with diastolic blood flow from the aorta to the left ventricle. Echogenic membranous stenosis was observed in the main pulmonary artery. Based on these findings, the dog was diagnosed with ALVT and type I supravalvular pulmonic stenosis.
Conclusion:
This is the first case report of ALVT in veterinary medicine that describes diagnostic imaging findings. ALVT should be considered in dogs with an aortic regurgitation murmur and can be detected by echocardiography.

Key words: Aortoventricular tunnel, Congenital heart disease, Dog, Echocardiography, Pulmonic stenosis