In Ontario it is the Innkeeper's Act. There is an automatic lien the moment payment is overdue. A notice of debt for horse commonly known as X, owned by XX and the amount to be paid by X date or that horse/tack will be sold at public auction. This usually gets a response. The horse must be sold at auction to prevent inside deals. Once the BO has collected the amount owing, he/she is also able to claim reasonable expenses such as the ad, trailering, etc. The owner is entitled to the remainder.