The former Norwich City forward has netted five times for the Owls this season, but will now be sidelined, starting with Saturday’s trip to Wolverhampton Wanderers.
Fellow striker Steven Fletcher also missed training earlier in the week, but returned today and is in contention for Molineux, along with Portuguese international Lucas Joao.
“Gary Hooper will be out for some time with his injury,” said Owls boss Carlos Carvalhal.
“He played very well last week (at Fulham), he is doing well and finding goals but this is the life, he is not available to play, we have more players to play in attack.
“We like to have all the players and Gary is an important player.
“It is good that Lucas (Joao) is back again, he is more ready than last week. He’s had around two and a half weeks of training.
“Fletcher was out during the week but he is training again. (Almen) Abdi was ill but we expect him training tomorrow and after that we will make decisions for the weekend.”
Left-back Daniel Pudil also missed last week’s 1-1 draw at Fulham, when winger Adam Reach was employed in defence, but could return on Saturday.
Carvalhal said: “Daniel Pudil is training OK, he still had limitations at the beginning of the week, he is getting better and better but he is back in training.”