But although a recovery period of six months has been suggested, the 24-year-old is hopeful to return to the starting XV ahead of schedule.
"It's probably too early to say definitively how long I'll be out," he said. "Prior to the operation, the surgeon is talking about a six-month window to get back but that's quite cautious and if I regain the strength at the same level as my right shoulder then it should be sooner."
Beattie is joined on the operating table by Glasgow team-mate and Scotland A cap James Eddie who faces a similar time out of the game after dislocating his shoulder in training.
And with the Warriors looking to improve on last year's third-place Magners League finish, head coach Sean Lineen must now instil his faith in their youngsters ahead of their opening game against Leinster on September 3.
He said: "We wish both Johnnie and James a speedy recovery and we're grateful for the expert medical attention they are receiving.
"Currently there are a number of bumps and bruises within the camp. Happily, however, our physiotherapists are confident that the vast majority of players on the treatment bench at the moment will be fit for our first Magners League game against Leinster in September.
"On the back of last season's endeavours and three summer tours with national teams in which we had 20 players involved, a number of our players have taken a few knocks. It's unfortunate but it's an opportunity for the youngsters to shine over the next few weeks."