It is not out of the realm of speculation and likelihood that while the verse is literal that a word or two can be symbolic...In this case it's possible the term horse can just be a form of transportation...Or, it really could be factual...
One of the northern countries allied against Jerusalem was a horse and mule merchant for Tyre, which was a city on the coast of, what is today, southern Lebanon:
"Tarshish was thy merchant by reason of the multitude of all kind of riches; with silver, iron, tin, and lead, they traded in thy fairs. Javan, Tubal, and Meshech, they were thy merchants: they traded the persons of men and vessels of brass in thy market. They of the house of Togarmah traded in thy fairs with horses and horsemen and mules." (Eze 27:12-14 KJV)
Judah and Israel were also merchants for Tyre.
Philip