The former Newport man was a crucial cog in the Glovers side that clinched promotion to the Sky Bet Championship last season but has been restricted to just seven appearances this term.
And Yeovil boss Gary Johnson says Foley, who has another year on his contract, will benefit from regular football.
"Sam hasn't played that much this season and has just come back from a little hamstring problem and is ready now but we feel he needs games," he said.
"He has gone to Shrewsbury for 28 days and once he's played those games hopefully he'll come back for the run-in.
"He has got a big part to play still and he has another year on his contract. Sam needs a little foray out so he can build up his week knowing he has a game at the end of it."
Johnson also confirmed that defender Joey Jones has extended his loan stay at Woking for another month.
- Sports & Recreation
- American Football
- Sky Bet Championship
- Gary Johnson