I always carry one of those cans of "air horn"as I think it might scare off any predators by the surprise of it. That's my theory anway. Recently at a school science fair there were some ladies from a local nature conservancy there with some different varities of owls. Some are quite small but some are huge. The "owl lady" said that a 4 lb owl can lift a 16 lb dog and that recently 4 dogs were killed by owls, one of which was on a leash
!! She said that some of the bigger owls are out during the day and not just at night.
Also a cayote got a dog in the subdivision behind ours and that quite a few cats have "gone missing".