I need some help. About 3 1/2 years ago my daughter rescued 3 pit-mix puppies who were about 8 to 9 weeks old. We found a home for one and ended up keeping the other two. One has grown up to be a kind, even tempered girl. Her sister, Marley, is also a very good girl for the most part. She has good manners, is obedient, and gets along with her sister & our new stray. The kittens have usually slept with her. She is fine with the teens coming and going, new faces and old regulars.
Marley, however, hated the bulldog, Eloise. Eloise had always assumed she was the one who called the shots. We kept them separated for three years, each having turns in and out of their space. With separation, they ignore each other. There is no growling or threatening. Last week, the two were accidently both left free. Eloise died as a result. a day or two later, Marley also went after a newish kitten who is very feisty: I came home to a huge fight, which ended with one sharp command. The kitten was bloody although not badly harmed, but he had been wildly fighting for his life when I walked in. She has dived for him several time since so now he and she have turns out. Marley also has begun to guard the room I put her in when Eloise had her turn out. One of the kittens she regularly slept with wandered into her room and Marley dived after her.
While Marley & Eloise's animosity is long standing, attacking the kittens (they are about 4 months old) and guarding "her" space is new this week. There haven't been any changes in food, household routines, or her health that are perceptible to me, except Eloise had recently been having more time out since she was 10 and needed to go out more frequently, but Marley still had the majority of free time.
Stories of dogs reporting unexpected attacks on their owners for no apparently reason seem to be something the press writes about. I could not find any information investigating why a dog would turn on the owner. How will I figure out Marley's perceptions in all of this? What evidence and clues should I be gathering? Should I be worried?
Thanks for listening. I am still deeply grieving Eloise and fear for Marley.
We don't have any trainers in the area. I need to know how to think about Marley. I do have a little fear of her now.