With the passage of the ban on slaughterhouses, more states are taking the matter into their own hands. For example, the Montana House of Representatives strongly endorsed—67 to 33—a bill recently that would green-light a horse slaughterhouse in Montana and aims to bring the industry back to the United States.

"This bill is really providing a humane and regulated processing plant," the sponsor, Republican Rep. Ed Butcher, a horse owner from the central Montana farm community of Winifred, told a Montana newspaper. "Demand is there. We want a humane way to address the problem."

The bill is on its way to the Montana State Senate.

In 2007, when the last three U.S. horse slaughterhouses were closed, a record 78,000 horses were exported to Canada and Mexico for slaughter, according to U.S. Department of Agriculture statistics compiled by the Humane Society.

The slaughterhouse issue has been a hot button in the U.S. horse industry, with some claiming that old and sick horses are simply being abandoned or are shipped to more inhumane slaughterhouses on the other side of the border.

Opponents of slaughterhouses would like to see them banned altogether.

House Majority Leader Margarett Campbell, D-Poplar, told the Missoulian in Missoula, Mont. that the closure of the country's last slaughterhouse "had a devastating effect on ranchers."

The Humane Society, however, notes that most horses that end up at slaughterhouses are not old and sick, but are in good condition (92.3 percent according to the USDA Guidelines for Handling and Transporting Equines to Slaughter) and will not be neglected or abandoned.