To earn amateur and/or youth points on a horse, many breed associations specify that the horse must be owned by the youth or amateur (or a member of their immediate family). As a result, many lessors actually take the step of signing a transfer of registration when leasing a show horse so that the horse can be shown by the youth or amateur and earn points. In most breed associations, transferring registration of a horse with no intent to actually transfer the ownership of the horse is strictly against the rules, and if caught, the perpetrators can be fined and/or suspended. Still, this practice is fairly common, and as you might imagine, it leads to all sorts of legal problems.
Because the parties rarely have anything in writing regarding the ownership transfer (or the lease, for that matter), the lessee may be able to successfully claim ownership of the horse. The lessee has possession of the horse, has been paying the horse's expenses, and has usually paid the lessor a lease fee. The lessee is also the registered owner of the horse. What does the owner have to prove that they own the horse? Often, the answer is nothing except an argument that the lease fee paid to the owner was far below the horse's fair market value and therefore no sale took place, and that argument may not win the day.