Ever had a lawsuit involving a horse? For example, have you ever had a horse and car collision case? A case where a person riding a horse got hurt? How about a case arising out of a breach of contract concerning the sale of a horse?
Here is a site that collects the law of horses. Really.
If you have a PI case that involves a person injured while riding horse be sure to read the Tennessee Equine Activity Act.
Indeed, there is even a list of law review articles on point.