Bruins general manager Peter Chiarelli said Monday at TD Garden that defenseman Johnny Boychuk  has a mild concussion after taking a hard hit from Senators forward Chris Neil Saturday.
The Bruins added two defenseman at Monday’s trade deadline in Greg Zanon and Mike Mottau, and when Boychuk is healthy, the B’s will have eight blueliners.
As for Nathan Horton , who is still out with a concussion, Chiarelli said that he expects the forward back before the end of the regular season, but that he isn’t certain.
“I expect him back, but with these things, I don’t know,” he said.
Chiarelli said that he would have liked to add two forwards at the deadline, but that the deals weren’t there to be made.