Donaldson aggravated a right calf injury in a 2-1 loss to the Baltimore Orioles on Thursday night at Rogers Centre.
"It’s very aggravating, very frustrating," Donaldson said. "At the same time, you’ve got to try to stay as positive as possible and look to get back in the right time and make sure that everything is going to be good."
Donaldson, the 2015 American League most valuable player, is batting .310 with two homers and four RBIs in nine games this season.
"Who knows how long it’ll be, hopefully it’s just 10 days," said Blue Jays manager John Gibbons. "But we had to do it. We needed to do it."
Donaldson hit .284 last season with 37 homers and 99 RBIs.
The Blue Jays can ill afford an extended absence for the veteran slugger.
Toronto was mired in a six-game losing skid entering Friday night’s home game against Baltimore. The Blue Jays’ 1-8 start is the worst in franchise history.
"I’m not going to set a timeline right now," Donaldson said. "It’s too fresh right now. I’ll know a lot more probably in the next few days. The important part is just making sure that whenever I do come back, it’s ready, and just go from there."
Coghlan, meanwhile, will likely be used in a utilityman role. He made his big-league debut in 2009 and split last season between the Chicago Cubs and Oakland Athletics.
"He’ll get some playing time, I can’t tell you yet how much," Gibbons said.
Backup infielder Darwin Barney started at third base on Friday night.