U.S. horses shipped to Mexico for slaughter more than tripled in 2007, after all three U.S. horse slaughter plants were closed, according to the Journal of the American Veterinary Medical Association. As of Dec. 20, 2007, 44,475 horses had been shipped to Mexico for processing. In addition, horse exports to Mexico for other reasons nearly doubled in 2007, raising concerns that these horses are being shipped for slaughter under false pretenses to avoid regulations. USDA estimates Canadian facilities processed 35,000 horses in 2007.

In 2006, USDA estimates that 138,206 U.S. horses were processed, according to the article. Of those, 102,260 were processed in the U.S., 24,866 in Canada, and 11,080 in Mexico.

The concern is the treatment of horses once they cross the border into Mexico, according to the article. "The reality is, proponents of this legislation (the American Horse Slaughter Prevention Act, currently pending in Congress) have done nothing to address the real issue here and, in fact, by seeking to ban horse slaughter, they have made things significantly worse," said Dr. Mark Lutschaunig, director of the American Veterinary Medical Association Governmental Relations Division.