Rio King euthanized after unknown injury

Rio King, who was claimed for $20,000 from a maiden race last October and was second in the Grade 3 San Francisco Mile at Golden Gate Fields in April, was euthanized earlier this month because of a spinal injury that caused hind end paralysis.

Trainer Samuel Calvario said on Wednesday that Rio King was found stricken in his stall at Pleasanton. After treatment and veterinary consultation, it was determined that Rio King could not be saved.

The cause of the injury was not known, Calvario said.

“He didn’t respond to the medication,” Calvario said. “He was the good horse in the barn.”

A 4-year-old colt, Rio King won 4 of 14 starts and earned $140,210. He was claimed by Huntertown Farm last October and subsequently earned $113,420.

Rio King won three consecutive starts at Golden Gate Fields from early February to mid-March. In the San Francisco Mile, Rio King closed from last of nine to finish a nose behind Balnikhov at 51-1.

Rio King finished fourth by 1 3/4 lengths in the All American Stakes at a mile on May 29 in his last start.