Collateral vessel development, following unilateral chronic carotid occlusion in the dog.

Because much of the data base describing the physiology of cerebral circulation is based on experiments using the dog as a model and because the functional response to occlusion of arteries supplying the head have been shown to be different in man than in dogs, it is important that the growth and development of the extracerebral collateral circulation in dogs be documented. Using the techniques of corrosion casting, collateral vessel development was evaluated in adult mixed-breed dogs, following 4- and 8-week periods of unilateral ligation of the common carotid artery or the external carotid artery. Neurologic deficits or severe ischemia was not observed in any of the dogs during the postoperative period. Extensive collateralization occurred between the ipsilateral vertebral artery, regardless of the occlusion site. In addition, numerous collateral connections developed between the same vessel from the contralateral side. Two main patterns of collateral vessel organization consistently developed. Initially, a collateral network of highly tortuous superficial vessels predominated. With longer survival times after occlusion, deeper and more uniform-diameter direct-collateral vessels developed.