UNUSUAL INTERNAL CAROTID-ARTERY BRANCHING THAT PREVENTED ARTERIAL-OCCLUSION WITH A BALLOON-TIPPED CATHETER IN A HORSE

A mare with hemorrhage caused by guttural pouch mycosis was treated by insertion of a balloon-tipped catheter into the left internal carotid artery. During recovery from general anesthesia, the mare had profuse epistaxis, and was anesthetized again to determine the site of hemorr hage. The affected guttural pouch was opened to confirm that hemorrhag e was from the left internal carotid artery. The mare was euthanatized , and, at necropsy, the balloon catheter was found in an aberrant bran ch that arose f rom the internal carotid artery and joined the basilar artery. The mycotic plaque was on the left internal carotid artery, d istal to the origin of the aberrant branch, so that the balloon did no t obstruct retrograde flow through the infected segment. Additional di ssection of the internal carotid artery before insertion of a balloon catheter is recommended to identify any aberrant branches. Ligation of aberrant branches at their bifurcation with the internal carotid arte ry is recommended to prevent both inadvertent catheterization and retr ograde flow from the cerebral arterial circle.