Glaus has been dealing with pain in his shoulder for about three weeks, but he aggravated the condition on a swing in Tuesday night's win over the Cubs. He was examined on Wednesday, when he received the diagnosis as well as a cortisone shot in the joint. Glaus also received a shot on Sunday, but the second one was localized in the area of the diagnosis.
"If the medication does what it's supposed to do, then in two or three days it will be fine," Glaus said. "Then we can strengthen it and keep going."
With two weeks remaining in the regular season and the Cardinals still in a pennant race, Glaus will play as soon and as much as he can tolerate. Precautionary days off are not a viable option at this point.
"It's all pointing in the right direction," Glaus said. "It should be fine in a few days, and when it's fine, we'll go."
Glaus is just one of a number of Cardinals hitters dealing with injury issues. Rick Ankiel is slowed by a lower abdominal injury, Joe Mather is out for the year with a wrist injury and Brian Barton is limited as he recuperates from a strained oblique muscle.
Nonetheless, the club does not expect to add any more players from the Minor Leagues. Manager Tony La Russa said that neither third-base prospect David Freese nor outfield prospect Colby Rasmus is in line for a promotion.
Felipe Lopez, Brendan Ryan, Brian Barden and Aaron Miles could all see third-base time in Glaus' absence. Lopez, however, might also be used in the outfield, La Russa said.
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.