How to deter coyotes from the area?

This is probably going to make it harder, but there's a feral colony of cats in the area too and I know that's likely what draws the coyotes. They're making life Hell right now. One of my mom's dog surprised one and she came back last week with her face was all torn up. She's perfectly fine now, the vet couldn't do much for her actually.They want to prevent this from happening again, any ideas?