HALLANDALE BEACH, Fla. – Trainer Mike Maker lost one of the most successful and beloved members of his potent stable after the 9-year-old Cross Border succumbed to an apparent cardiac arrest during a routine training session early Thursday morning at Gulfstream Park. The incident occurred just five days after another veteran multiple graded stakes winner in Maker’s barn, Endorsed, was vanned off with a fractured sesamoid after pulling up following a five-furlong workout last Saturday.     Maker reported Thursday that although his racing career has ended, Endorsed is doing well after undergoing successful surgery to repair his injury earlier this week. The 7-year-old Endorsed, who was breezing in preparation for his final start of the season in the $125,000 Mr. Prospector Stakes on Dec. 23, was in the midst of a banner campaign that included victories here last winter in both the Grade 3 Fred Hooper and Grade 2 Gulfstream Park Mile. He also had finished fourth the previous season in the 2022 Pegasus World Cup. A son of Medaglia d’Oro, Endorsed retires with seven victories from 36 starts and earnings of more than $970,000. Cross Border was just galloping when stricken approaching the wire shortly after the racetrack opened for training Thursday. The 9-year-old gelding was a 13-time winner from 53 career outings, his two most notable victories coming in the Grade 2 Bowling Green at Saratoga in 2020 and 2021. A former $20,000 claimer by English Channel, Cross Border had amassed lifetime earnings of more than $1.3 million. “Cross Border was having a routine gallop this morning when it appeared he had heart failure,” Maker siad. “He was a horse who never had an issue and just loved his job. It’s crushing. Gut-wrenching for all of us. "Fortunately, Endorsed is doing well after having surgery to repair his fractured sesamoid. He was also a great horse for us, one who loved it at Gulfstream Park. We were getting him ready to run in the Mr. Prospector later this month.”     Maker also reported that he lost another member of his stable Wednesday evening at Turfway Park when Tazawako had to be euthanized after rearing in the starting gate and striking his head prior to the start of the final race on the card. “Obviously, this is the toughest part of the job, it’s hard to process, but somehow you just have to find a way to go on,” Maker said. :: Want to learn more about handicapping and wagering? Check out DRF's Handicapping 101 and Wagering 101 pages.