predatory foxes and stray dogs? I've read that dogs will kill them.

a fence. that a fox or dog cannot fit under and is sturdy enough that the goats cant knock it down. basically enything that will secure the goats in an area where the small and big dogs and foxes cant go.

Build a good strong fence and get some sheep dogs to protect them. put barb wire on the top of the fence also.

I agree with dumdog. I have used Donkeys in the past, changing fencing can be costly and time consuming Donkeys are great but don't forget they are an animal too and need all the basics ie/ worming, feet trimmed, teeth checked(at least once every few years ideally ever year but it is just a protector after all hehe) and will need a vets attention for any mishaps But don't take me the wrong way I think Donkeys are the best way to go. But they do need maintence.