Skeleton Bones - Is it a horse or a donkey?

I have found a skeleton on my land right next to the fields where horses and Donkeys used to be kept. Its is quite small and although I have not excavated the entire skeleton yet, there is a horse or donkey shoe which is quite small and looks as though it would fit a small foal however young foals are not normally given shoes. The teeth look very horsey but I am not am expert. What are the main differences between the skeleton of a donkey and the skeleton of a horse? Also, is there any way I can tell what it is by just looking at the teeth as I haven't got the entire skeleton? Any tips and advice on excavating would be great, thanks!