I've only boarded in one barn in which I saw a padlock on a stall door. Perhaps at other barns boarders weren't delinquent, or perhaps the barn owner just didn't have a flair for the dramatic statement.
Barn owners put padlocks on stall doors when the horse owner hasn't paid for the horse's care and upkeep. This provision is typically included in the boarding agreement so that the horse owner has notice.
I have always hated padlocks because I just think: what if there was flood, fire, earthquake, tornado, or other freak occurrence in which the horse needs to be removed immediately from the stall, but the person at the stable doesn't know where the padlock key is kept, or the barn owner has gone out to the grocery store.
Interestingly enough, the padlock is considered to be a "peaceful means" of keeping the legal owner of the horse from removing the horse.
While I don't necessarily think it is a good idea to keep a non-paying horse on the property (it may be better to have the horse removed, then sue for the balance owing), in some situations it might be.
When a horse owner fails to pay past due board the barn owner has an automatic general lien on the horse.
According to California Civil Code Section 3080.02:
In addition to any other rights and remedies provided by law, a lienholder may:
(a)Retain possession of the livestock and charge the owner for the reasonable value of providing livestock services to the livestock until the owner's obligations secured by the lien have been satisfied.So if the horse owner shows up to take the horse away, and you as the barn owner have an automatic lien, then you can peacefully prevent the horse from being removed (such as by locking gates, or asking the horse owner to leave); you as the barn owner have the right to call law enforcement to prevent removal of the horse.
In my opinion, it is always better to keep contentious situations from escalating- do this by ensuring that boarders understand and have signed the terms of the boarding agreement, communicate clearly and often with your boarders, and prevent board bills from growing too large to pay off easily.
As always, you must continue to care for the horse while it is in your stable even if you are not being paid, otherwise you would be subject to criminal animal welfare prosecution.
If you choose to use a means of "locking" the horse onto the property I would recommend getting a Notice of Lien from the courts and posting it to the stall door so if the horse owner calls law enforcement to help take the horse you can provide the notice to the officer.
Have you ever seen a padlock on a stall door?
Or seen an alternative method used?