We have a 3 year old, 120 pound GSD named Major. He is mild mannered and loves everybody yet he is a fiercely loyal mama protector. We adopted an 18 month old GSD from a kill shelter so Major has a buddy to play with. Preacher is emaciated (about 30 pounds under weight) and we are working with him to slowly build his muscle and gain weight.
We introduced the dogs but Preacher would have no part of butt sniffing and immediately attacked Major. Major coward and slinked away. We have to keep Preacher in a metal crate or on a leash while in the house or outside.
Two days ago, Preacher was playing ball with me and nipped me by accident while he was giving me the ball. Major came unglued on Preacher. Preacher is no match for Major and Major had Preacher down in a heartbeat. He didn't hurt Preacher, just had him down and let him know that he is not one to be messed with. Preacher was submitting quickly. I gave Major the command to let go and he did. Herein lies my grief:
As soon as Major let go of Preacher, Preacher was in attack mode on Major and the fight lasted less than 15 seconds while I tried to break up the fight. Major had Preacher back down but wasn't hurting him. In the meantime, I got bite four times on my side (serious puncture wounds) and my hand was tore up (18 stitches).
Now every time Preacher sees Major, he growls and lunges at him. Major stays away from Preacher's "area". Major is not afraid of Preacher, he just doesn't want conflict.
What can I do? What did I do wrong and how can I rectify this?