Rescued a 7 mos old 90 pound male St. Bernard puppy. I have 2 other dogs. A German shepherd mix and small terrier mix. Our new pup gets overly excited and starts getting very rough with them. I know he wants to play but he takes it to an obnoxious level and starts chasing them. They are terrified of him now. I have a giant crate coming tomorrow. I can’t leave the house with him running free. I’m worried he will hurt one of them. He’s not neutered. I have a vet appt tomorrow for pre op. Will that help? Has anyone had this issue? We Adopted a Saint Bernard mix a year ago from the shelter. He was 8 and extremely laid back. He passed away from cancer. Any advice or insight would be appreciated.