Howe injured his knee in a collision with GWS midfielder Jacob Hopper midway through the fourth quarter in the Magpies two-point defeat to the Giants.
Buckley told reporters after the game that the early diagnosis was that Howe suffered damage to his medial and posterior cruciate ligaments.
“We won’t see him for a while, I don’t think,” Buckley said in his post-game press conference.
“He’s been great. He’s a great leader, a great player. I’m devastated for him.
“He puts a lot into his footy – he invests all of himself into it – so you are going to lose people as you go along, through a season, at different times, and we will have to cover – and we will – but right now … Howey’s devastated,” Buckley said.