Code of Federal Regulations Title 9. Animals and Animal Products § 9.88.3 Standards for conveyances

(1) Be designed, constructed, and maintained in a manner that at all times protects the health and well-being of the equines being transported (e.g., provides adequate ventilation, contains no sharp protrusions, etc.);

(2) Include means of completely segregating each stallion and each aggressive equine on the conveyance so that no stallion or aggressive equine can come into contact with any of the other equines on the conveyance;

(3) Have sufficient interior height to allow each equine on the conveyance to stand with its head extended to the fullest normal postural height;  and

(4) Be equipped with doors and ramps of sufficient size and location to provide for safe loading and unloading.