How do I train this resource guarding? New shelter dog.

Scenario 1: I’m on the couch petting new dog. Old dog walks up and new dog growls. Old dog minded his own business.

Scenario 2: I’m on the bed with new dog. Old dog gets on the bed. New dog growls a bit. Old dog lays down on the bed.

I know shelter dogs need understanding, love and patience. I know they need time. I just don’t know what to do in these scenarios to promote the correct behavior. I would like to feel more confident about it all. He is a sweet boy who acts like he’s never been around other dogs. I’ve had him for three weeks and he’s seen the vet.