KENNETT SQUARE, Pa. - For eight months, Barbaro took fans of horse racing and lovers of horses on a bumpy ride of hope and worry as he struggled to recover from devastating injuries suffered in the Preakness.

That struggle ended Monday as Barbaro, the Kentucky Derby champion from Maryland, was euthanized at New Bolton Center veterinary hospital. He was 4 years old.

Barbaro's surgeon, Dr. Dean Richardson - brushing away tears and with his voice breaking - said that, in the end, Barbaro's discomfort was just too great, as infection spread to his previously unaffected front legs.

“It was more than we wanted to put him through,” Richardson said at a news conference at New Bolton. “We intensified all pain medication and continued to through this morning, but we couldn't succeed.”

The horse's fight had evoked the passion of fans in and outside the sporting world. His battle proved more inspirational than his six racing victories - including the biggest winning margin in the Kentucky Derby in 60 years.

“Until (Sunday) night, he had been an exceptionally calm and relaxed horse who would lay down and sleep,” Richardson said. “But (Sunday) night, he was clearly in distress. He wasn't comfortable laying down or standing up. You could see he was a different horse. You could see he was upset.”

At 10:30 a.m., with owners Roy and Gretchen Jackson in his stall talking to him gently, Barbaro was euthanized by Richardson.

“We were all there. He knew us,” Richardson said. “My guess is he ... ”

Richardson stopped to compose himself before continuing.

“He was in the sling,” he said. “He was comfortable. He ate his grass. He was alert and aware. At that point, he was given a very heavy dose of a tranquilizer and then an overdose of an anesthetic ... It couldn't have been any more peaceful.” Gretchen Jackson said: “Grief is the price we all pay for love. I'd like all of us to say a prayer for Barbaro, and I hope we can turn our love into an energy to help all horses throughout the world. I hope each of us will find a path to support the horse.”

The end came 37 weeks after Barbaro broke down in the first furlong at Pimlico Race Course on May 20, fracturing his right hind leg in three places and shattering the pastern bone just above the hoof into 20 pieces.

Complications were layered upon complications throughout the ordeal. Barbaro required five-plus hours of surgery May 21 just to repair the fracture.

He needed another surgeryJuly 8 to fight an infection in his right leg. Five days later, Richardson acknowledged the horse had laminitis, an often fatal infection that can destroy the hoof. Richardson described Barbaro's chances for survival at the time as poor.

Throughout Barbaro's treatment came daily deliveries of fruit baskets, apples, pears, carrots and flowers at New Bolton Center as well-wishers squeezed closer for any view of the colt. Thousands signed giant get-well cards.

By early August, after more than two months in intensive care, Barbaro made it outside for 20-minute grazing sessions.

By November, the cast was removed from his lower right leg. Then, on Dec. 13, Richardson projected that Barbaro might leave the hospital in the “not so distant future” because his condition had improved so much.

But the dark bay took a turn for the worse in the second week of January. There were two procedures to remove damaged tissue from his left hind hoof, the site of his laminitis. On Jan. 13, a cast was placed on his right hind leg for more support.

On Wednesday, that cast was replaced with a custom-made plastic and steel brace.

On Saturday, Richardson performed a third surgery on the right rear leg. Barbaro had developed an abscess in the right rear hoof as a result of the continuing laminitis problem in the left.

Richardson inserted two steel pins in one of the three bones that had healed since May to eliminate all weight bearing on the right foot. The cast was replaced by an external brace, or skeletal fixation device.

The last-ditch attempt was not enough. Monday morning, there were signs of laminitis in Barbaro's two front legs.

“It was a difficult decision to make, but it hinged on what we said all along,” Richardson said. “It was about his quality of life and whether we had any reasonable expectation of saving him ... In the last 24 hours, he developed fairly severe laminitis in both front feet that left him not a good leg to stand on.”

The horse racing community understood how much of a long shot it was for Barbaro to recover completely.

Dick Small, a veteran Maryland trainer, said: “There were so many people rooting for him after he was injured, but it was sort of like hoping for a miracle, like in church. They just don't happen very often.”

To an extent, the horse's dramatic tale of survival obscured his impressive accomplishments on the track.

“It'd be nice if he's remembered for winning the Kentucky Derby, not for breaking down in the Preakness,” said Peter Brette, Barbaro's exercise rider and assistant trainer, to the Associated Press.

Given Barbaro's Kentucky bloodlines, his success was not a surprise. His sire was Dynaformer, out of the mare La Ville Rouge. Dynaformer was bred for distance and La Ville Rouge for speed. Together they won 13 races and nearly $1 million.

Barbaro earned $2.2 million for his six victories. He started his career in October 2005 as a little-known colt by winning at Delaware Park and Laurel Park.

It was Barbaro's half-length victory in the Florida Derby in April that raised his profile for the Triple Crown series and the Kentucky Derby.

In Louisville, he stunned the racing world with the Derby's fastest final quarter-mile since Secretariat in 1973. He won by nearly seven lengths in a 20-horse field.

Before the Preakness, trainer Michael Matz said: “The biggest thing Barbaro has going for him is his will to win, his heart.”

Barbaro proved that at Pimlico. He broke through the starting gate prematurely but was quickly brought up. On the second try, calamity struck.

Less than 200 yards into the race, Barbaro wobbled in obvious pain. Only jockey Edgar Prado's quick action to rein him in saved the horse from immediate destruction.

“(Barbaro) knew he was hurt and he relaxed for me,” Prado said.

As Matz tended to Barbaro on the track, Pimlico fans screamed, “No! No! No!” and “Don't you kill that horse!”

Barbaro was taken by van to New Bolton Center, where a team of seven inserted a titanium plate and 27 screws to piece the leg together.

“It's not about money,” Gretchen Jackson said at the time. “It's not about limelight. It's more about the horse and its beauty and integrity on a lot of levels.”

Roy Jackson reiterated that sentiment Monday, saying as far as he and his wife were concerned, “There is nothing we would have done differently.”