The Blues have lost eight of their past 11 games, including a 6-1 loss to the Vancouver Canucks on Sunday, which likely helped fuel the flaring of tempers.
Bortuzzo unloaded three rights on Sanford before coaches moved in to separate the pair.
"That happens," Blues interim coach Craig Berube told reporters. "Guys are frustrated, and they should be. So sometimes in practice, it boils over and things happen. That's what happens because they do care and they want to be successful and they want to win."
Blues winger Patrick Maroon didn't seem too bothered by his teammates' scrap.
"That's part of hockey, right?" Maroon said. "We're still teammates. Sometimes people get heated and frustrations build up. I love that stuff. I think it's great. That's me, though. I don't know if anyone else likes it."
The Blues, who are now 10-14-4, host the Florida Panthers on Tuesday night.