The defender suffered ankle ligament damage during Sunday's pre-season friendly against Brora Rangers at Dudgeon Park and is expected to be sidelined for several weeks.
Perry was thrown into the action as a substitute at half-time but came off worst in a collision with Ryan Watson and left the pitch on a stretcher.
According to the club's website, the 23-year-old has been ruled out for "the foreseeable future", before adding: "At present, the Rangers management are resigned to being without him for weeks rather than days and that's a huge setback for manager Ally McCoist."
Better news for Rangers was the return of Andy Mitchell to training this morning after jarring his ankle at the weekend, while Sebastien Faure was also involved after missing the Brora clash through illness.
A double from Lewis Macleod helped secure a 2-0 win over the Highland League side and McCoist was also impressed with trialist Bilel Mohsni.
Asked if he could do a deal with the French-Tunisian, the Gers boss told Sky Sports News: "I hope so. I was very impressed with him actually.
"I thought he came in and looked solid with Emilson [Cribari] at the back and they mopped everything up that came their way.
"With the injury to Ross, we put him back on in the second half and he was very comfortable.
"He's a strong boy, he can handle the physical side of the game and there is certainly a physical aspect to the Scottish game.
"That won't be a problem for him - he will handle that fine."
Central defence is an area McCoist is keen to strengthen for the assault on the Second Division and he added: "If I could get two centre-backs, I would be delighted with that."
However, McCoist has confirmed his pursuit of Christophe Berra is now over.
He revealed last week the former Wolves defender was on his wanted list, along with Bosnian international Boris Pandza.
McCoist now expects Berra to remain south of the border but says Pandza is still on his radar.
The Light Blues boss told several newspapers: "The deal for Christophe is now off.
"There is nothing in that at all - I think he's going to a Championship club.
"The club is still taking to Boris Pandza's agent and I have spoken to the player.
"There's still a long way to go but he's a player we are interested in."