Late Saturday, the 3-year-old colt, who shattered his leg at the start of the Preakness on May 20, had the titanium plate and a number of screws replaced after developing discomfort in the leg and a "consistently" high temperature.

The surgery was performed by Dr. Dean Richardson at the University of Pennsylvania New Bolton Center, where Barbaro has been recovering in the intensive care unit.

In a statement released Sunday, Richardson emphasized that the complications are "potentially serious."

"Barbaro had developed some discomfort and a consistently elevated temperature so we believed it was in his best interest to remove the hardware and thoroughly clean the site of the infection," Richardson said. "We also applied a longer cast on that leg for additional support."

It is the third procedure in less than a week for Barbaro. He had the cast on his injured leg replaced and some new screws inserted Monday, and on Wednesday another new cast was applied. Also, Barbaro is being treated for a small infection on the sole of his uninjured left hind hoof, according to the hospital.

Richardson said Barbaro's main fracture is healing well, but the pastern joint—a joint above the hoof—continues to be a concern. The joint was stabilized with "new implants and a fresh bone graft."

Barbaro took longer to recover from the anesthesia from this latest procedure, Richardson said. But he said the colt was back in his stall and receiving pain medication, antibiotics and "other supportive care."

Barbaro's owners and trainer continue to visit twice daily, the statement said.

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