Double-deck trailers may not be used to transport slaughter-bound horses to from U.S. farms and feedlots to other way points en route to foreign processing plants under a new rule announced by the USDA Animal and Plant Health Inspection Service (APHIS) on Sept. 7.

Horse processing has not taken place in the U.S. since 2007 when the last processing facility operating the country was shuttered; however, since then, horses have been transported to Mexico and Canada for processing.

Some animal welfare advocates have long considered double-decker horse trailers inhumane because their configuration is not high enough for the animals to stand with their heads extended to the full normal postural height. Interstate highway regulations requiring a 14-foot minimum vertical clearance under overhead structures precludes double deck transports from being high enough to accommodate equines.

Existing USDA/APHIS regulations ban the use of double-decker trailers to transport slaughter-bound horses directly from the U.S. to processing plants in Mexico and Canada. The new rule expands the existing regulation to include the transport of horses from U.S. farms and feedlots to other intermediate points en route to slaughter