Updated

Barbaro's condition was "potentially serious" Wednesday, and the Kentucky Derby winner's veterinarian said the colt was "facing tough odds" in an effort to recover from catastrophic injuries.

Dean Richardson, the chief surgeon at the University of Pennsylvania's New Bolton Center, said doctors were looking at all possible treatments to keep Barbaro comfortable several days after the 3-year-old colt had his cast changed for the fourth time in a week.

"Our entire staff is determined to do all they can for this magnificent horse," Richardson said in a statement issued by the George D. Widener Hospital for Large Animals.

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Barbaro, who shattered three bones in his right hind leg at the start of the Preakness Stakes on May 20, has undergone three surgical procedures in the past week. In the most recent one Saturday, Richardson replaced the titanium plate and 27 screws and also treated several infections — one in the injured leg and a small abscess on the sole of his uninjured left hind hoof.

"Today we will focus on further diagnostics and keeping our patient comfortable," Richardson said.

Barbaro's recovery had been going smoothly until this recent series of setbacks. Saturday's surgery lasted three hours, and Richardson replaced the hardware that had been inserted into the leg May 21, the day after the Preakness.

"He's facing tough odds and his condition is guarded," Richardson said.

A major concern centers on the infection in the right rear pastern joint — located above the hoof that was shattered into more than 20 pieces. While most of the fractured bones have healed, the joint that connects the long and short pastern bones remains problematic.

"There's so much concern. It's significant," Richardson said in The Washington Post on Wednesday. "Two weeks ago, we were at 50-50 [for survival]. With this new problem, we are less than that."

All decisions are being made after consulting with owners Gretchen and Roy Jackson, the statement said.