one additional thought
You might also want to check with the folks in Reynoldsburg, OH that issue the coggins reports, can’t remember the name but I think it is a branch of the Ohio Ag Dept. Will look when I get home and send you a note with their phone no. The coggins reports may be public records, in which case you won’t need a subpoena to get copies of the reports.
Added Sat. morning: coggins reports in Ohio are issued by the Ohio Dept of Agriculture, Division of Animal Industry, 8995 E. Main, Reynoldsburg, OH 43068. There is a place for owner’s name and address, but more importantly, the section below that is “horse stabled at”. A written request for a search in that field by address would most likely be the info that the Dept needs if it is able to search under that function.