Earlier on Friday, Dyson was placed on the 15-day disabled list and outfielder David Lough was recalled from Triple-A Omaha in a corresponding move.
Dyson incurred the injury while attempting to catch Mike Trout's home run in Wednesday night's 9-5 victory over the Angels at Anaheim. The move is retroactive to Thursday, an open date for the Royals.
Lough, also a left-handed batter, had a .340 (52-for-153) average for the Storm Chasers with three home runs, three triples, six doubles, five stolen bases and 17 RBIs in 36 games. He plays all three outfield positions and started Friday night's game in right field.
It's a tough break for the 28-year-old Dyson, who recently was getting playing time after opening the season as the team's reserve outfielder. He had started five of the last eight games as manager Ned Yost sought an alternative for Jeff Francoeur, who is 4-for-34, .118, in May. Yost was using Dyson in center and shifting Lorenzo Cain to Francoeur's spot in right field.
In his last three starts, the speedy Dyson had been in the leadoff spot. Overall, he was hitting .268 with eight RBIs and six stolen bases in seven attempts. He banged a three-run homer against the Yankees on May 10 in an 11-6 loss, just his second in the Majors, but his great speed was his primary weapon.
"He's getting better and better and better all the time," Yost said last week.
After he was injured, the Royals intended to have him examined in Oakland but that plan was changed.
"When he woke up, it was actually a little more sore, which is not always a good thing, especially for a speed guy," Yost said.
He was sent home so the nature of his injury could be determined through an MRI and other tests.
Dyson apparently hurt his ankle as he jammed his right foot against the wall padding and hoisted himself up in a vain attempt to catch Trout's drive. He had no chance, however, because the ball appeared to be several feet out of reach. Dyson hung on the fence momentarily, as if delaying contact with the ground on the injured leg.
He left the game after the eighth-inning incident, limping as he walked in from the outfield. He was the first Royals player to be placed on the 15-day disabled list since the season began.
Lough, 27, got his first Major League experience with the Royals last September and had a .237 average in 20 games. For Omaha last season, Lough hit. 275 with 10 homers among his 40 extra-base hits and collected 69 RBIs.
In 2009, Lough led the entire Kansas City organization with a .325 average for Class A Wilmington and Double-A Northwest Arkansas, winning the George Brett Hitter of the Year Award.