I’ve only been involved with one case where all the animals were required to be removed but it was more so because the couple left the state and all the animals behind. They left a minor child to care for the animals and did not leave any money for living expenses/food/etc, One could argue about the parents’ mental status, but it was not due to dementia.
The other case that comes to mind I was not directly involved in, it was many years ago and a few states away, happened to be in the area and heard of the volunteer opportunity through a friend of a friend of a friend, so I don’t know how it was exactly handled from the start, only the little snippet of what I saw and heard from the other volunteers. It was an elderly couple who were both suffering varying levels of dementia, and they had barns full of horses. Quite a breeding farm in its day. The wife was the one who was more with it and was handling things, up to a point. I never saw the husband. I don’t know how the community did it, but what I gathered during my time there volunteering (cleaning stalls that hadn’t been cleaned in maybe years, you climbed uphill immediately on entering the door), was that they had organized volunteers and did have some kind of law enforcement involved, probably animal control too. They started with no big changes, keeping the horses there, not threatening to take them. Made sure the animals had the basics immediately - hay/water/vet/farrier care, organized turnout if they could, got the barn operating again, checked on the owners daily - someone on site all day, done in shifts. They didn’t do everything at once and they didn’t have too many people on site at once either, one step at a time, I’m guessing so the owner wasn’t overwhelmed. At some point they were able to convince her to sell some, marketed them with full disclosure - she did run a breeding farm, so maybe it was easier since she had sold off stock in the past. It wasn’t a walk in the park, however because she would agree to sell one, then maybe forget she had agreed and refused when the new owners showed up. This is where the law enforcement part /animal control part came in, they would be there ahead of time for every sale, to explain what was happening, make sure no one took advantage of her, organize the paperwork and be mediator if necessary. I think they spent a lot of time with her, she seemed comfortable with them - they seemed to know each other well, maybe a small town / everyone’s your friend thing. She also had some trusted people around her - not sure if they were related, employees, or just long-time volunteers, but what I could tell, if she had an episode, they never forced her or pushed her into selling right there and then. It would take hours sometimes before the papers were signed and the horse loaded. Nothing done behind her back because they said she would pick up on it and lose trust, want everyone off the property. I don’t know how they did it, but it seemed if she had forgotten, they would sit with her and have a discussion each time, taking it slow. Maybe let her go in the house for a while then pick it up again in a few minutes or a few hours. The plan was to get her down to x number of horses, no more breeding, and always have help on site to handle everything until she got to a point where she spent more time in a dementia state than as herself, at which point then the farm would be sold. When she was herself, she knew every single horse and every little detail about their life. Thanked each and every volunteer for what they did. She seemed like a very sweet lady who really cared for each and every horse, and they were her family, so it was pretty hard to see her when she was confused, angry, and not recognizing her animals. I really credit the volunteers I met; they worked really hard, seemed very empathetic to the situation, and just really went all out to help everyone (the people and animals) involved. I don’t know if it was always like that, but it was for the short time I was there. I don’t think it was easy.
I also don’t know if that’s the only way to deal with things, but it seemed to be working for this case. I saw moments when it seemed like it wasn’t working, but she would come around and be ok with whatever eventually - selling a horse, moving a horse to a new stall, any change could set her off and just as quickly she’d come back and be ok with it. It could be because of where she was in her dementia, I really don’t know. I have no idea how they got the volunteers either, or how long they kept it up or if/when the farm sold.
Good luck with your relative. I imagine it will be hard but hoping that it isn’t. It will be worth it though. Thank you for caring and trying to do something.