http://www.bloodhorse.com/horse-raci...-work-in-ocala
RE: Classic Empire
"The Pioneerof the Nile colt has refused to breeze twice since being scratched Feb. 19 from the March 4 Xpressbet.com Fountain of Youth Stakes (G2) due to a hoof abscess."
Hoof abcess or any foot ailment seems like as good a reason as any for a runner to not change leads properly. I only know of these kind of issues when it's media reported for a stakes level horse.
Makes me want to ask how many on a typical card go to the gate within 30 days or so of being treated for hoof ailments. I expect it is very common but I don't know. Most runners appear to change instinctively when in top form. Recovery from those type of injuries might explain some form reversal and layoff winners!