We have coyotes everywhere and haven't had any issues with them attacking cattle, horses, chickens, ducks, people or any other creatures on our farm. I live fairly close to the forest, with ridges and such that coyotes live in.
Canines are smart animals, I'm sure they could have driven the cow into the barbed wire fencing. Or perhaps the cow just didn't see it and tried to get away. If food is very scarce, they could try and get harder prey like a horse. Most canines hunt in packs, from what I know. If natural food isn't there, they might try to get something from a farmer or a rancher. They'd probably go towards poultry first, then maybe cows, and if they had to horses. I think horses would be last resort, if there is one [or a very small group] out alone in a smaller pasture away from high-traffic areas.
Just my thoughts with my experiences. Our land isn't hunted much, so they have there own prey. Our horses have a pasture closer to the roads, and the barns are pretty much front-and-center with traffic going by them constantly. We have multiple farm dogs that are outside, and we have quite a few smaller dogs [not toy breeds, but smaller herders] that are fenced in. I don't think I coyote would even want to mess with us, or have any reason to. But different places have different deals. That's why I don't like the idea of a huge pasture out of sight. Not that we have the land, but coyotes and other factors can take a toll on the animals if they're too far out.
Last edited by ButtInTheDirt; 02-16-2011 at 01:42 PM.