The valuable checking forward needs surgery to repair a dislocated right shoulder suffered in Saturday's 3-1 win over Detroit.
"We'll probably have to lose him for an extended period of time to rectify the problem so that he's good for the long-term, ready down the stretch and in the playoffs," Oilers GM Kevin Lowe told The Canadian Press on Wednesday.
Lowe said Moreau would undergo surgery within the next couple of weeks once the swelling goes down. Moreau also had surgery on his left shoulder a few years back.
But Lowe doesn't think Moreau will be lost for the entire season.
"We've got the best therapists around here," Lowe said from Edmonton. "We've got an incredible history of successful rehabs. I'm not a doctor, but my guess is anywhere between three and four months. Sure that's the better part of the regular season, but it's one of those things that had he injured it later in the season he'd probably tried to get by with a brace or something."
Moreau could have opted for rehab instead and come back sooner but would have also risked the shoulder popping out again.
"Since it's early enough, we figured let's get it done now so he can be ready for down the stretch and the playoffs," said Lowe.
The 31-year-old Moreau dislocated the shoulder when he threw a punch at Red Wings defenceman Danny Markov late in Saturday's game, retaliation for a huge open-ice hit on Oilers centre Jarret Stoll earlier in the game. Lowe isn't frustrated by how Moreau got hurt.
"That's hockey," Lowe said. "I'm sure if he had to do it all over again he would do it the same way. That's why he's so desirable as a player because he does things like that."
If the Oilers are going to suffer an injury, forward is where they can take a hit. Edmonton has been carrying 14 forwards this season and has plenty of depth to deal with an injury. Winger Raffi Torres got bumped up from the fourth line to take Moreau's spot on the third line for Wednesday night's game at Anaheim.
"We should be fine," said Lowe. "There will definitely be nights where we'll miss Ethan and what he brings but we'll get him healthy and 100 per cent."