treat aggression

[ARPdrummer]

A couple months ago I started fostering a dog named Max from the local humane society. At that point he was a great dog, only issues were normal young puppy issues such as pottying in the house, getting into things, etc. After a few weeks he finally found a home with another dog, a border collie, that was about his age. Everything seemed to be working well for them and I went on to foster 2 other dogs. After the last one found a home I got contacted that Max was being brought back to the humane society because of him fighting with their other dog. Apparently they had always had to keep their treats separate but one day they forgot a treat in the back yard. They found both dogs fighting over it and after that day Max kept going after the other dog.
I brought Max home with me yesterday and everything seemed to be going well. Only problem was him annoying my own dog, which you expect from a puppy. Today, however, I decided to bring home some bones that both the dogs loved and in the past I NEVER had a problem with either of them fighting over them. And today seemed to be going fine, until Max was almost done with his bone and noticed a bone laying next to my dog, who wasn't even chewing on it and he decided to attack her. So I ended up having to lock him up in a crate, pick the bones up and let him out again and everything was fine.
I would like to train him out of this habit so he can find a permanent home. I have no idea how the behavior started. As I said he had no aggression whatsoever when I first started fostering him. My dog and him would have treats and bones laying around all the time and never once did one even try to pick a fight. The only thing close was when my dog would get protective of her bone and growl but nothing else, and Max would just back off and go chew on something else. Then he gets adopted and ends up with this behavior, so I have no way of knowing what brought this on.
Any advice would be greatly appreciated as I would like this dog to get a home and not end up where he was.

[Mike D'Abruzzo]

Have you read the section in the self help section on "pack structure" and the section on "dog culture" in "knowledge. Understanding the problem will be key here and if any adopter follows the rules in those sections they should be fine if that is Max's only problem. He didnlt show the behavior at first because of the partcular lower ranking relationship he had at that time. The reason he is showing the behavior is normal, but what is abnormal is that Max seems to be doing more than the minimum amount necessary to reinforce or prove a position that he believes he has or believes is up for grabs. the solution is to give the humans in the household the leader role and there should no longer be anything for Max to prove / enforce.

The relationship building exercises in the aggression rehab section will relate as well.