What does Clinton Anderson teach about tying a horse to a trailer and what are the safety rules?

Clinton Anderson addresses trailer tying specifically because it is one of the most common contexts where horses pull back and injure themselves, and he has documented the specific setup that prevents most trailer-tying accidents. The first and most important rule Anderson teaches is that a horse must be confirmed to tie — meaning it has been taught to accept halter pressure without pulling back, ideally through the blocker tie ring system or through extensive patience pole work — before it is ever tied to a trailer. Tying an unconfirmed horse to a trailer is asking for a trailer-pulling incident. The horse that pulls back with enough force can pull the trailer, tip it, injure itself seriously, or break equipment in ways that create additional danger. For the tie height and length, Anderson is specific: the horse should be tied at or above wither height, and the lead rope should be short enough that the horse cannot get a leg over it or get its head down to graze but long enough to allow the horse to hold its head in a natural, comfortable position. A rope tied too long creates wrapping and entanglement risk; a rope tied too short creates neck tension that keeps the horse uncomfortable and more likely to pull. Anderson recommends using a blocker tie ring for trailer tying — a device that allows the rope to slip gradually under extreme pressure, preventing the horse from hitting a hard stop that triggers the full pull-back response. The blocker tie ring has reduced trailer-tying injuries significantly in barns and show environments where it has been adopted. He also teaches never to tie a horse to a part of the trailer that is not structurally solid — not to a door handle, a latch, or a ramp that is up. The horse should be tied to a purpose-built tie ring that is welded or bolted to a structural part of the trailer frame.