9 C.F.R. § 95.36

(a) Transportation companies or other operators of cars, trucks or other vehicles carrying import products or materials moving under restriction, other than those in tight cases or casks, shall affix to and maintain on both sides of all such vehicles durable placards not less than 5 1/2 by 6 inches in size, on which shall be printed with permanent black ink and in boldface letters not less than 1 1/2 inches in height the words “Restricted import product.” These placards shall also bear the words “Clean and disinfect this car or truck.” Each of the waybills, conductors' manifests, memoranda, and bills of lading pertaining to such shipments shall have the words “Restricted import product, clean and disinfect car or truck,” plainly written or stamped upon its face. If for any reason the placards required by this section have not been affixed to each car, or the billing has not been marked by the initial or the connecting carrier, or the placards have been removed, destroyed, or rendered illegible, the placards shall be immediately affixed or replaced and the billing marked by the initial or connecting carrier, the intention being that the billing accompanying the shipment shall be marked and each car, truck or other vehicle placarded as specified in this section from the time such shipment leaves the port of entry until it is unloaded at final destination and the cars, trucks or other vehicles are cleaned and disinfected as required by § 95.37.

(b) If it is necessary to unload enroute any of the materials or products transported in a placarded car, truck or other vehicle as provided in this section, the car, truck or other vehicle from which the transfer is made and any part of the premises in or upon which the product or material may have been placed in the course of unloading or reloading shall be cleaned and disinfected by the carrier, in accordance with the provisions of § 95.37, and the said carrier shall immediately report the matter, by telegraph, to the Deputy Administrator, Veterinary Services, Washington, DC 20251. Such report shall include the following information: Nature of emergency; place where product or material was unloaded; original points of shipment and destination; number and materials of the original car or truck; and number and initials of the car, truck or other vehicle into which the product or material is reloaded in case the original car or truck is not used.