I have two Jack Russell’s, they are litter-mates, they have always been together, and I’ve owned them since they were puppies. They are 10.5 years old, a boy and a girl. My boy has developed some cloudy eyes and has trouble going up and down the stairs so someone usually carries him. My female has become very aggressive towards him and picks fights a few times a day, when she hears him either being carried/coming down the stairs she starts growling and then attacks him if I don’t pick her up. I’m not sure why she is doing this or what to do about it. She is very possessive of me and acts differently if I’m not home. Please help, I don’t know what to do.