Acclamation came out of a Monday gallop with a slight swelling in the area of the left front ankle that will prevent a title defense in the $1 million, Grade 1 Pacific Classic on August 26, according to owner/breeder E.W. "Bud" Johnston.
"Three days ago we were thrilled with the way he was looking and acting, then he came out of a gallop with a slight filling," Johnston said. "It might just be a lousy little strain, but it could develop into something serious and it's probably going to keep us out of the Pacific Classic. We're only concerned about what's right for the horse."
Deadline for Pacific Classic nominations is Thursday.
"We probably won't even nominate," Johnston said.
On Sunday, trainer Don Warren indicated that Acclamation would have a workout either Wednesday on the Polytrack main surface or Thursday on the turf course. The injury changed everything.
"He had some heat in a pastern," Warren said early Wednesday morning. "It could be a minor infection, but we're having it checked out. We'll just have to wait and see until we get a report from the vets later this morning or this afternoon."
Acclamation, a six-year-old California-bred son of Unusual Heat owned by the Johnstons' Old English Rancho and Peter and Mary Hilvers, won both the Grade 1 Eddie Read Stakes on grass and the Pacific Classic on Polytrack in 2011 in becoming Del Mar's Horse of the Meeting en route to winning the Eclipse Award for champion older male.
Acclamation currently owns a seven-race win streak, capturing two starts in 2012, the most recent being a successful Eddie Read title defense on July 21. He has earned $1,958,048 from a 30-11-2-6 career line.