Genuine Reward, one of only two offspring of 1980 Kentucky Derby winner Genuine Risk, was euthanized on Wednesday afternoon at Old Friends Farm near Georgetown, Ky., according to Michael Blowen, the founder of the farm. Genuine Reward, whose health declined precipitously over the past two weeks, according to Blowen, was 25. Genuine Reward, who was bred by Mr. and Mrs. Bertram Firestone, the owners of Genuine Risk, was moved to Old Friends in 2015. He quickly became a popular attraction at Old Friends, as a rare representative of a mare who, in 1980, was only the second filly to win the Kentucky Derby. “He was as kind and as sweet and as gentle and as intelligent as any horse we had,” Blowen said. “We moved him to the front of the farm because he was so beautiful and popular, and it certainly helped that he looked just like his mom.” Genuine Reward, a chestnut by Rahy, never made a start as a racehorse, but he made headlines as one of only two horses ever produced by Genuine Risk, who was inducted into the Hall of Fame in 1986. Genuine Risk’s record as a broodmare was marred by a series of unsuccessful matings, miscarriages and stillborn foals, and Genuine Reward, born in 1993, seemed to represent a hope that the popular mare could pass on her genes to a next generation. But he could not come close to living up to the expectations placed on him. He suffered colic as a foal. Placed in the barn of Bill Mott, he had injuries to his shins. He was eventually retired at age 4 without ever having made a start. He had a brief stallion career in Virginia, but eventually wound up in Wyoming, as a sire of polo ponies. In 2015, Laura Hillenbrand, the author of the best-selling book “Seabiscuit,” bought Genuine Reward after he was retired in Wyoming and offered for sale on Craiglist. Hillenbrand arranged for the horse to be retired to Old Friends. Genuine Risk’s only other foal, Count Our Blessing, was born in 1996. He also never raced, was gelded, and turned into a show horse. Genuine Risk died at the age of 31 in 2008. Blowen said that Genuine Reward began exhibiting serious physical problems in the beginning of August, and that his health declined quickly without responding to medications. “It was probably a lot of things,” said Blowen. “He started going downhill really fast. And I’ve learned that these horses tell you when it is time. It was time.”