Dog help please!

This is whiskey. My so brought him home from work BC he wonder up and the boss was gonna haul him off. We knew nothing about him. We think he's around 5 or 6 yo and we know he's been wild for a while. He is a good dog beside every time we open the gate he goes running out. He always comes back. Its been over a year since we had him and he has came a long way but I'm sick of him getting out mainly BC our other dog we had since 6 weeks old whines and barks till he is back in. What can I do to stop this? Would getting him cut help or is it too late? Thank you for your help