KENNETT SQUARE, Pa. — Barbaro's eyes were so bright for so long, his appetite so voracious, even the surgeon who lovingly cared for the Kentucky Derby winner believed the colt would overcome his broken bones and ailing feet.

"I thought many times that he was going to make it, absolutely," Dr. Dean Richardson said Monday after Barbaro was euthanized because of complications from his breakdown at last year's Preakness. "But at the same time, I was smart enough to know all these challenges were there throughout."

A series of ailments, including laminitis in the left rear hoof, an abscess in the right rear hoof, as well as new laminitis in both front feet, proved too much for the gallant colt.

When Richardson checked Barbaro on Monday morning, the eyes that had been so full of life were darker, a sure sign of distress. After consultation with owners Gretchen and Roy Jackson, the colt was given a heavy dose of a tranquilizer and an overdose of an anesthetic and put down at 10:30 a.m.

"You could see he was upset," said Richardson, chief of surgery at the University of Pennsylvania's New Bolton Center. "That was the difference. It was more than we wanted to put him through."

Barbaro's eight-month ordeal, which made him even more of a hero than he was as a champion on the track, was over.

"I really didn't think it was appropriate to continue treatment because the probability of getting better was so poor," Richardson said.

Fighting back tears, he added: "Barbaro had many, many good days."

"Certainly," Gretchen Jackson said, "grief is the price we all pay for love."

The bay colt underwent nearly two dozen surgeries and other procedures, including cast changes under anesthesia. He spent time in a sling to ease pressure on his legs, had pins inserted and was fitted at the end with an external brace — extraordinary measures for injuries that most horses never survive.

Weeks of positive reports turned into months. Barbaro was eyeing the mares, nickering, gobbling up his feed and trying to walk out of his stall. But Richardson warned there still could be trouble, and by mid-July, his greatest fear became reality — laminitis struck Barbaro's left hind leg.

On Sunday, a day after Barbaro's fight for survival had reached a critical point, Richardson compared the various injuries to a "house of cards." One part falls, and the rest start to crumble.

In this case, it was the laminitis that attacked both front feet that left him vulnerable.

"That left him with not a good leg to stand on," Richardson said.

Roy Jackson added: "We just reached a point where it was going to be difficult for him to go on without pain. It was the right decision, it was the right thing to do. We said all along if there was a situation where it would become more difficult for him, then it would be time."

With dark red roses on the table at an afternoon news conference, Richardson and the Jacksons were emotional talking about the colt. Many staffers welled up, and by early evening the lobby was overflowing with roses and other assorted flowers sent by grieving fans.

The scene seemed to mimic months earlier when Barbaro became America's No. 1 patient after he first suffered his catastrophic injuries.

On May 20, Barbaro was rushed to the New Bolton Center, about 30 miles from Philadelphia, hours after shattering his right hind leg just a few strides into the Preakness Stakes. He underwent a five-hour operation that fused two joints, and Richardson called the colt's chances a "coin toss."

The recovery, though, seemed to go well. The bones that had shattered in the Preakness were healed and the only major concern was in Barbaro's left rear leg, where 80 percent of the hoof had been removed in July when he developed laminitis.

Then a deep abscess in the right hind hoof began causing discomfort last week, and surgery was required to insert two steel pins in a bone to eliminate all weight bearing on the ailing right rear foot. With two ailing hind legs, Barbaro's front legs had to handle even more weight and that's when laminitis struck again.

"This was a very near thing," Dr. Rick Arthur, the equine medical director for the California Horse Racing Board, said. "If it hadn't been for the last cascade of complications, I think this could have been successful. The key thing is the fracture healed. It was laminitis to the left hind that started the sequence of events that led to his demise."