Shotgun Kowboy, an 8-year-old who established himself as one of the top horses from Oklahoma, has been retired from racing, his breeder, owner and trainer, C.R. Trout, confirmed to Daily Racing Form on Friday.  Oaklawn publicity on Friday reported the retirement due to a fractured sesamoid. Trout told Daily Racing Form that X-rays taken Thursday revealed the injury. He said the fracture was in the left front leg. Trout on Tuesday said he was scratching Shotgun Kowboy out of a Friday allowance at Oaklawn due to a cough. He said on Friday that he found the horse was not putting weight on his left foreleg Thursday, which led to the diagnostics.   Trout said Shotgun Kowboy will simply be given time to let the fracture heal. He is retiring to Trout’s farm in Edmond, Okla. “He’ll be my best buddy,” said Trout, whose wife, Arletta, died in November.  Trout said Arletta named Shotgun Kowboy, an Oklahoma-bred by Kodiak Kowboy and the mare Shotgun Jane. Shotgun Kowboy won 15 of 40 starts for earnings of $1,548,684, according to Daily Racing Form statistics. He registered eight of those victories in stakes races, his biggest wins coming in the Grade 3 Oklahoma Derby and the Grade 3 Lone Star Park Handicap. The horse won four runnings of the Oklahoma Classics Cup at his base of Remington Park in Oklahoma City.