Obsession with dog. Suggestions on how to break this attachment?

I am a caregiver and my patient has a small dog. Before I took her into my care she was stuck in a basement with the dog and her for 2 years. She has Alzheimer's and Dementia and the relationship with the dog is unhealthy. She calls him her son and says he talks to her, she will take him out and as soon as we come in forgets we just took him out. She forgets we feed him and takes food and hides it in drawers and under furniture throughout the house. She walks around constantly following the dog and telling him she’s sorry and how good he is. A lot of her conversations don’t make sense and she constantly says I don’t know and this one and that one and the man and the kids, I think she is delusional. The dog doesn’t speak to her but she says he does and she tries to force it to do things it doesn’t want and has to constantly have him in her site or sitting beside her or thinks he needs something more when he’s well taken care of. I’m at a loss and need some advice on how to break this attachment. Any suggestions? Please it’s becoming very unhealthy for her and the dog