Adam Arkfeld writes, "This tusk was recovered in a wet clay bed formed by runoff from limestone bedrock. The ivory has been completely mineralized. It appears that the horse was carved when the tusk was still "green." The level of carving detail would not be possible on limestone."
Magdalenian period carved ivory and bone figures from Europe depict bridled horses. The Virginia example may be depicting the same, including a bridle rein extending along its "neck."
I propose the incised lines illustrated by the white marks on the gomphothere tusk may represent a simple bridle and rein on the horse figure. Pleistocene human control of the horse is suspected in Eurasia but not in North America. With this interpretation of this find, it may be worth considering this possibility here.