Robert Griffin III after suffering a concussion Sunday (Toni L. Sandys/The Washington Post)

Coach Mike Shanahan said he thought rookie quarterback Robert Griffin III had a good practice Wednesday as Griffin recovers from the concussion he suffered Sunday.

But Shanahan said the Redskins must prepare both for the possibility that Griffin will play Sunday against the Minnesota Vikings at FedEx Field, and for the possibility that he won’t.

“You have to look at both ends of it,” Shanahan said.

Griffin did not take his usual number of practice-field reps but did take a significant amount, according to Shanahan, who called Griffin’s participation in practice limited.

Shanahan declined to say if rookie backup Kirk Cousins took all of the first-team snaps in Wednesday’s practice not taken by Griffin, or if some snaps went to veteran third-stringer Rex Grossman.

He played down the difference in the offensive approaches that the Redskins would take with Cousins playing rather than Griffin playing.

Shanahan said there are a few plays the Redskins run with Griffin that they wouldn’t use with Cousins, but that’s it.

The Vikings, Shanahan said, know both Cousins and Grossman from their preseason appearances, and know based on media reports that Griffin should be ready to go Sunday unless he suffers a setback this week.

Shanahan continued to defend the Redskins’ use of the term “shaken up” in an injury update announced during the game Sunday to initially describe Griffin’s condition. The NFL is looking into whether the Redskins complied with league guidelines requiring teams to provide accurate and timely injury information during games.

“We’ll try to go with the correct language from now on,” Shanahan said.

— Cornerback Cedric Griffin is getting better, Shanahan said, but still is plagued by a hamstring injury.