Negligence claim for injuries caused by roaming animal requires proof of negligence

In our class last night, we discussed strict liability claims for injuries caused by animals.  Interestingly, here is a report from Day on Torts on a case involving a roaming horse. In this case, the plaintiff was injured when her vehicle collided with a horse on a dark roadway. The defendant landowner proved that he had fenced in the horses and had no explanation for how or why the horses had escaped. Neither did the plaintiff and, since plaintiff must prove that the horse owner was negligent in allowing the horse to be on the road, the court held the defendant was entitled to summary judgment. The plaintiff simply failed to prove one of the elements of the cause of action.

There is nothing strange about this ruling. The question I have is why did the plaintiff not sue under a theory of strict liability?  I assume the answer to my question is somewhere in the law of Mississippi.  For example, I wonder if whether by statute or common law, horses are considered domesticated animals or pets in Mississippi.

The case is called Ladnier v Hester and it is available here.