"We just reached a point where it was going to be difficult for him to go on without pain," co-owner Roy Jackson said. "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."
A series of ailments, including laminitis in the left rear hoof and a recent abscess in the right rear hoof, proved too much for the gallant colt.
Barbaro battled in his ICU stall for eight months. The 4-year-old colt underwent several procedures and was fitted with fiberglass casts. 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. These were all extraordinary measures for a horse with such injuries.
Roy and Gretchen Jackson were with Barbaro on Monday morning, with the owners making the decision in consultation with chief surgeon Dr. Dean Richardson.
"I would say thank you for everything, and all your thoughts and prayers over the last eight months or so," Jackson said to Barbaro's fans.
On May 20, Barbaro was rushed to the New Bolton Center, about 30 miles from Philadelphia in Kennett Square, hours after shattering his right hind leg just a few strides into the Preakness Stakes. The bay colt underwent a five-hour operation that fused two joints, recovering from an injury most horses never survive. But Barbaro never regained his natural gait.
January had been a tough month for Barbaro, reports The Early Show's veterinary correspondent Dr. Debbye Turner.
He suffered a significant setback over the weekend, and surgery was required to insert two steel pins in a bone — one of three shattered in the Preakness but now healthy — to eliminate all weight bearing on the ailing right rear foot.
Most horses in Barbaro's condition would have been euthanized, reports Turner.
The procedure Saturday was a risky one, because it transferred more weight to the leg while the foot rests on the ground bearing no weight.
The leg was on the mend until the abscess began causing discomfort last week. Until then, the major concern was Barbaro's left rear leg, which developed laminitis in July, and 80 percent of the hoof was removed.
Richardson said Monday morning that Barbaro did not have a good night.
Brilliant on the race track, Barbaro always will be remembered for his brave fight for survival.
The story of the beloved bay colt's fight for life captured the fancy of millions.
When Barbaro broke down, his right hind leg flared out awkwardly as jockey Edgar Prado jumped off and tried to steady the ailing horse. Race fans at Pimlico wept. Within 24 hours, the entire nation seemed to be caught up in a "Barbaro watch," waiting for any news.
Well-wishers young and old showed up at the New Bolton Center with cards, flowers, gifts, goodies and even religious medals for the horse, and thousands of e-mails poured into the hospital's Web site just for him.
"I just can't explain why everyone is so caught up in this horse," Roy Jackson has said time and again. "Everything is so negative now in the world, people love animals and I think they just happen to latch onto him."
Devoted fans even wrote Christmas carols for him, sent a wreath made of baby organic carrots and gave him a Christmas stocking.
The biggest gift has been the $1.2 million raised since early June for the Barbaro Fund. The money is put toward needed equipment such as an operating room table, and a raft and sling for the same pool recovery Barbaro used after his surgeries.
The Jacksons spent tens of thousands of dollars hoping the best horse they ever owned would recover and be able to live a comfortable life on the farm — whether he was able to breed or not.
The couple, who own about 70 racehorses, broodmares and yearlings, and operate the 190-acre Lael Farm, have been in the horse business for 30 years and never had a horse like Barbaro.
As the days passed, it seemed Barbaro would get his happy ending. As late as December, with the broken bones in his right hind leg nearly healed and his laminitis under control, Barbaro was looking good and relishing daily walks outside his intensive care unit.