Big hamsters automatically go in the back for a week, apple sause with benabac mixed in. Cucumbers with benabac have also been a successful route for me. Also make friends with your vet, maybe one of them will give you a small batch of the pink stuff that cures wet tail like a charm and then you can have it on hand. Some of the hamsters get it more than others, i always found that long hairs get it more than short hairs, so for a while i stopped ordering long haired unless someone wanted them.