How do I evaluate and maintain a horse trailer for safe transport?

A horse trailer is one of the highest-stakes pieces of equipment a horse owner uses, because the consequences of trailer failure can be catastrophic for both the horse and the people involved. Regular evaluation and maintenance of the trailer is a direct contribution to the safety of every trip. The floor of a horse trailer deserves the most careful and most frequent inspection because it is subjected to constant moisture from urine, manure, and cleaning water, and wood floors in particular deteriorate from the inside in ways that are not visible from the trailer's interior. A floor that appears sound from the inside can be structurally compromised from the outside. Pressing firmly on every section of the floor and inspecting the underside of the trailer periodically identifies developing rot before it reaches the point of failure. The hitch system — the coupler that attaches the trailer to the tow vehicle's ball, the safety chains, the breakaway cable for brake-equipped trailers, and all connecting hardware — should be inspected before every trip for wear, corrosion, and correct function. A hitch system that has not been inspected is a hitch system whose condition is unknown. Tire condition, including inflation pressure and tread depth, affects both fuel efficiency and safety. Trailer tires that sit for extended periods without use can degrade internally without showing obvious external signs — a trailer that sits for months should have its tires inspected before significant trips, not simply inflated to the correct pressure and assumed to be serviceable.