Ah I see, he's ripped the outer part of the horn off but not the core, which is the living bit - that explains why he doesn't have a hole in his skull. That's not so bad. If it happens again to a sheep, you can collect clean cobwebs and wrap them round the exposed core to stop the bleeding. You can buy a similar haemostat dressing at the chemist - worth keeping in stock if you have horned sheep. Once it's dried up, he should have no bother.