Join Date: Jun 2008
Location: SJ Newfoundland, Canada
So, why can't you take the dog? Or at least your mom? If its a matter of the dogs not getting along then more training and socialization is needed. Afterall, YOUR the Alpha dogs and YOU decide who is in your pack, that means everyone needs to get along.
Unfortunately, your sister's dog will need to live somewhere else. As everyone stated, the instability and fact that he came from a mill are triggering his behavior. He will need to live with someone who understands dogs more than "I worked very hard to make him realise the grass is okay".. I know your sister loves her dog but everyone needs to act more assertive in dealing with him. This includes having him live with socialsed dogs ( at your mom's?) and getting him socialised with a trainer who is experienced with dealing with ill-bred dogs. I'd say professional training is all you need to have all the dogs live together. Either that, or worst case scenario- get rid of the dog altogether.
I don't like to discuss re-homing. Obviously, your sister cannot have a dog if it's an unstable environment. To the dog, the alpha leader (your sister) is only around for 2 days biweekly. This does not give the dog anything to hold onto making his life harder.
Blah, I'm just rambling now. Sorry!