(defendant appeals summary judgment in a personal-injury case; defendant collided with a horse on roadway late at night; defendant owns horses; defendant admitted no knowledge of how the horses escaped; defendant admitted she witnessed no problems with the plaintiff's fence; court noted the defendants produced no evidence that plaintiff was negligent; Barrett v. Parker, 757 So. 2d 182 (Miss. 2000), held it could be conceivable for a cow to escape and enter a roadway and the owner not be negligent; court affirmed summary judgment for the plaintiff).