Arturo Mares, a Southern California-based exercise rider, died Thursday of complications from injuries sustained while exercising a horse Jan. 27 at Santa Anita, according to his son, Israel Mares. Arturo Mares was unseated when his mount stumbled while jogging, trainer Hector Palma said last weekend. Mares sustained severe neck and head injuries in the accident, according to his son. Mares was treated by paramedics on the track before he was transported to nearby Huntington Memorial Hospital. Mares’ condition deteriorated late Wednesday and early Thursday before his passing, Israel Mares said. “He had fractured his neck,” Israel Mares said. “He had a really bad brain injury. He was starting to have complications on top of the brain injury.” Israel Mares said his father had lost movement in his arms and legs. Arturo Mares was born in Mexico City in 1959. He turned 65 on Monday, his son said. Mares rode at Caliente in Tijuana, Mexico, south of San Diego, in the 1980s before moving to California at the end of that decade, his son said. Riding from 1976-90, Mares won 311 races from 3,858 mounts. He rode briefly at Hollywood Park in 1989 and 1990. In recent decades, Mares was an exercise rider at Del Mar, Hollywood Park, and Santa Anita, his son said.  “He was a good guy,” Palma said Friday. “I really feel sorry.” Mares is the second exercise rider to die of injuries sustained during training in Southern California in the last four months. Arturo Luevano, 53, died as a result of injuries sustained when he was unseated at Los Alamitos in October. Israel Mares said his father will be cremated. No plans for a memorial service have been finalized, he said. “We wanted to take our time and think it over,” Israel Mares said. Arturo Mares’s survivors include a wife and three sons. In the days since the accident, Israel Mares said his family has been overwhelmed by an outpouring of support from the racetrack community. “That’s the one thing I find comfort in,” Mares said. “A lot of people appreciated him as a person and a friend. It’s really nice to hear and see that people cared about him.”