Hore was assisted from Casey Fields after being tackled at training, with the 24-year-old eventually undergoing further assessment to diagnose the extent of the knee injury.
“This is devastating news for Marty and the club, as he was preparing for the season ahead.
“Marty is a very impressive and resilient person, and we will fully support him through his rehab.
“He’ll meet with the surgeon next week to discuss the appropriate treatment required to repair the ACL.”
Hore made his debut with the Demons in 2019, going on to play 14 games for the club before toe and quad injuries ruled him out of playing the entire 2020 season.