That struggle ended yesterday morning, as the Kentucky Derby champion trained in Maryland was euthanized at the New Bolton Center veterinary hospital.
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 laminitis developed in his previously unaffected front legs.
"It was more than we wanted to put him through," Richardson said at a news conference at the University of Pennsylvania Hospital for Large Animals at the New Bolton Center. "We intensified all pain medication and continued through this morning, but we couldn't succeed."
The horse's courageous fight had evoked the passion of fans inside and outside the sporting world. His battle proved more inspirational than his six racing victories, including the biggest winning margin in the Derby in 60 years.
"Until [Sunday] night, he had been an exceptionally calm and relaxed horse who would lie down and sleep," Richardson said. "But [Sunday] night, he was clearly in distress. He wasn't comfortable lying down or standing up. You could see he was a different horse. You could see he was upset."
So, at 10:30 a.m., with Richardson and Barbaro's owners, Roy and Gretchen Jackson, in his stall, talking to him gently, Richardson euthanized the horse.
"We were all there. He knew us," Richardson said. "My guess is he ... "
Richardson paused to compose himself.
"He was in the sling," Richardson 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 - who had trained at Fair Hill Training Center near Elkton - broke down May 20 in the first furlong of the Preakness Stakes at in Baltimore, fracturing his right hind leg in three places and shattering the pastern bone into 20 pieces.
Complication followed complication throughout the ordeal. Barbaro required more than five hours of surgery on May 21 just to repair the catastrophic fracture.
He needed more surgery July 8 to fight an infection in his right leg. Five days later, Richardson acknowledged that the horse had laminitis, an often-fatal infection that can destroy the hoof. Richardson described Barbaro's chances of survival as poor.
Throughout Barbaro's treatment, there were daily arrivals of fruit baskets, carrots and flowers at New Bolton Center as well-wishers squeezed closer for any view of the valiant 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. On Dec. 13, Richardson projected that Barbaro might leave the hospital in the "not so distant future" because his condition had improved so much.
The Jacksons began looking for a permanent residence for their star horse, somewhere beyond their farm in West Grove, Pa., where he could enjoy life and still be seen by his many fans.
Gretchen Jackson called Barbaro "America's Horse" and said it would be unfair to put him someplace where his fans wouldn't be able to see him.
But this month, the 4-year-old dark bay took a turn for the worse. 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, the cast was replaced with a custom-made plastic and steel brace.
On Saturday, with the horse foundering, Richardson performed a third surgery on the right hind leg. Barbaro had developed an abscess in the 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 hoof. The cast was replaced by an external brace, or skeletal fixation device.
The last-ditch attempt was not enough. Yesterday 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."
Throughout the days of hopeful reports from New Bolton, often followed by words of caution, the horse racing community understood just 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 fight for 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," Peter Brette, Barbaro's exercise rider and assistant trainer, told 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, 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, 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 sent 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 yesterday, saying, "There is nothing we would have done differently."
firstname.lastname@example.org email@example.comSun reporters Kent Baker and Mike Klingaman contributed to this article.