How long has he been on that medication for now, and what sort of exams has your vet conducted to really observe what’s happening? I know you said your rabbit is neutered, and this may sound like a dumb question but I want to confirm that your vet has said “He’s neutered” or your vet did the neuter.

You said you’ve tried everything for litter box training, but specifics will be needed so the community can chime in to see what helps. I’m unsure of Benjamin’s pain-situation (if he feels pain when picked up?) but I find the most effective method for litter box training is not only relocating the poos, but also the rabbit him/herself. For some rabbits this is not an option because they will not tolerate this. Other items is making feeding items exclusively in the litter box, as rabbits like to pee/poop where they eat.

This also brings up the neutering point again because typically a neutered rabbit will pick up litter training (if done properly) relatively quickly. I know Benjamin was brought up originally because he was having urination issues, so part of it could be, due to his inability to control his bladder, he may not be able to “seem” litter box trained.

Also, don’t see it as “he refuses to use the litter box”. Rabbits don’t understand litter boxes. Even litter box trained rabbits probably see it more as “Oh, that’s a place I can go potty and I feel comfy there, and I can eat there too. Nice.” They aren’t too intelligent, but their inclination to go to the bathroom in the same place makes litter training and litter box use possible. At the moment, Benjamin doesn’t see your designated litter box as his go-to place.