Angiographic Variation of the Internal Carotid Artery and its Branches in Horses

OBJECTIVES: To record the angiographic anatomy of the equine internal carotid artery (ICA) using angiography techniques. STUDY DESIGN: In vitro descriptive study. SAMPLE POPULATION: Equine cadaver specimens (n = 50). METHODS: Head and neck specimens from horses of mixed breed, age, sex, and use without a history of guttural pouch disease had carotid and cerebral angiography using conventional (n = 7) and rotational angiography (43). Angiographic findings were verified by arterial latex casts. RESULTS: Variation in ICA anatomy was categorized into 4 groups: (1) the internal carotid and occipital arteries arising as a common trunk; (2) an aberrant branch of the extra-cranial ICA connected to the basilar artery; (3) an aberrant branch of the ICA ramifying into the surrounding tissue and not connected to any other vessels; and (4) an aberrant branch of the ICA giving rise to several smaller satellite branches, including connections to the caudal branch of the ipsilateral occipital artery. CONCLUSION: Rotational angiography is useful for identification of anatomic variation in the ICA that could be important in achieving vascular occlusion in the treatment of guttural pouch mycosis.