Single left coronary ostium and an anomalous prepulmonic right coronary artery in 2 dogs with congenital pulmonary valve stenosis.

A coronary artery anomaly characterized by the presence of a single left coronary ostium with absence of the right coronary ostium and an anomalous prepulmonic right coronary artery course was observed in two dogs with concurrent congenital pulmonary valve stenosis. This unique coronary artery anatomy is similar to the previously described single right coronary ostium with anomalous prepulmonic left coronary artery, the so-called type R2A anomaly, in that an anomalous coronary artery encircles the pulmonary valve annulus. Both dogs of this report, a boxer and an English bulldog, were of breeds known to be at risk for the type R2A anomaly. As such, veterinarians should be aware that the echocardiographic presence of a left coronary ostium in a dog with pulmonary valve stenosis does not exclude the possibility of a prepulmonic coronary artery anomaly that may enhance the risk of complications during balloon pulmonary valvuloplasty. A descriptive naming convention for coronary artery anomalies in dogs is also presented, which may be preferable to the older coding classification scheme.