You could try teaching him to leave things, but it takes time. Once you've got the basics of it, you can apply it to situations like making him leave his toys alone on your command and then advance to making him leave electra alone.

To do this you can start by placing a treat on the floor with your hand right next to it (so you can quickly cover it up if he goes for it) and say "leave it" only once for every treat because overuse will make the word meaningless. After saying it, wait for his reaction. Everytime he goes for it, just cover it. He will scratch at it and it may take awhile, but when he leaves it, and doesnt try to go after it uncovered for about 3 seconds immediately give him the treat and praise him. Repeat this quite a few times. Once he has gotten this down, he should be able to go for a while with the treat sitting right in front of him. Be patient and always praise a lot.

After Rusty has mastered this, try making him leave his toys and eventually situations with other dogs, like Electra.

My dogs are really good with this and it definately comes in handy because they don't get along with other dogs outside of their own "pack". Hope this helps!