Foxes are good at digging under fences so the chicken house will need protection from them getting in from underneath. Don't give up I know it is upsetting, do a bit of research on the best fox proof chicken houses. As Flo says geese are good guard dogs (or that guard geese) so may be worth looking in to that (not sure if geese are good at detering foxes but worth looking in to).

Sissy keep posting here, as we'll all lend a friendly ear, and maybe come up with some helpful suggestions.