I have horses and have seen coyotes in the pasture with them several times horses blow and snort coyotes DONT pay any ATTN horses let dogs chase them till they have had enough A horse will flat kill a dog I think there is more to this

A pet dog is not trying to KILL a horse either!
Much less a PACK of yotes, whose whole intention is to kill!

Throbak is correct. Something not right about that story. Something had to be wrong with the horse to begin with, or the coyotes wouldn't have messed with it.. We have a TON of horses in our 'hood, and none have every been messed with by coyotes.

Here's one:

http://denver.cbslocal.com/2013/05/20/2-children-attacked-by-coyote-in-colorado-springs/

Here is more also..... http://bigdeerblog.com/?p=2550

Comment thread in that first story mentions reports that the horse was already dead or down, which would make more sense. I know some areas of MI are starting to get pretty serious wolf populations going, so an attack on a healthy horse would more likely be wolves than coyotes.