—Lisa, Lexington, Kentucky
A.It is difficult to make suggestions without much more information about Leo’s history and management. I would recommend having an in-depth consult with an equine behaviorist to help you figure this out—either an Animal Behavior Society-Certified Applied Animal Behaviorist or a veterinarian who is board-certified in behavior and experienced with horses.
Pacing and especially digging indicates that Leo is considerably stressed over something. Examples I have known over the years of sudden onset of this type of behavior in a previously comfortable environment were mostly social stress associated with changes in stall arrangements, etc., which I imagine you would have recognized and mentioned in your question.
Other odd situations I can remember include fairly negative experiences in that environment: stray electricity, static electricity from a synthetic blanket, and exposure to a wild animal (pig, sheep, snake, mountain lion in barn). In the meantime until you figure it out, if at all possible, I would recommend leaving him turned out 24/7 where he is happy.