During a routine immunization visit for a 2 year-old neutered male Newfoundland dog, a systolic ejection-type (crescendo-decrescendo) murmur is detected. It is audible loudest on the left side of the chest between the 2nd and 5thintercostal (IC) space and at the thoracic inlet lateral to the trachea. Which condition is highest on a differential diagnosis list?
在对2岁的雄性已绝育纽芬兰犬进行常规免疫检查时，你检测到收缩期（渐强 - 渐弱）杂音。 在第二和第五肋间（IC）以及气管侧面的胸腔入口处，胸部左侧听起来最响。 哪种情况在鉴别诊断列表中排最前？
Find out the answer by clicking on one of the listed choices. Good luck!
点击列出的选项找出答案，祝大家好运
A - Pulmonic stenosis 肺动脉狭窄
B - Mitral dysplasia 二尖瓣发育异常
C - Tricuspid dysplasia 三尖瓣发育异常
D - Aortic stenosis 主动脉狭窄
E - Patent ductus arteriosus (PDA) 动脉导管未闭