We have a blind 8 year old Cocker Spaniel mix that didn't get along well with other dogs before he went blind. Now he does not like to be around other dogs at all. Due to an emergency we are pet sitting a very friendly 2 year old dog. She is not bothered by the older dog, but he will not accept her. We let her wander the house when he is in a bedroom or outside with the hope he will get used to her smell, but he lunges at her if we try to put them in the same room. (We always have them on leashes so we can pull him back.) It's a lot of work to keep them seperated and we will have her for several more weeks. Any suggestions?