Dorsoventral angiogram of the cerebral arterial circle of a donkey. The basilar artery was not straight and leaning more to the right side. Note the presence of the right caroticobasilar artery (arising from the second curve of the internal carotid artery). 1 internal carotid artery; 2 intercarotid artery; 3 caudal communicating artery; 4 basilar artery; 5 caroticobasilar artery