Which equine nematode was historically the leading cause of equine colic due to its impact on the cranial mesenteric artery?

Strongylus vulgaris is recognized as the leading cause of equine colic historically due to its ability to migrate and cause significant damage to the cranial mesenteric artery. This nematode, particularly problematic in young horses that have not been adequately dewormed, can cause blood vessel occlusion and resultant ischemia to the intestines, leading to severe colic or abdominal pain. The migration of Strongylus vulgaris larvae through the arterial walls can result in thrombosis and potentially life-threatening complications.

The other nematodes mentioned, such as Strongylus edentatus and Parascaris equorum, do have their own health impacts, but they do not have the same level of association with colic due to vascular complications. Equinococcosis, on the other hand, is primarily a concern in canines and not a significant cause of colic in equines. Therefore, Strongylus vulgaris is distinctively noted for its historical impact on equine colic through its effects on the cranial mesenteric artery.