Since 2005, Congress has prevented the commercial slaughter of horses in the United States by blocking the use of federal money for horse meat inspections.
It was routinely included in the annual Agriculture Appropriations bill after the original amendment to defund horse slaughter inspections enjoyed bipartisan support and passed by large margins (269-158 in the House and 69-28 in the Senate).
The 2012 Agriculture Appropriations Bill has not included this provision, and was signed into law by President Barack Obama on November 18.
"This is distressing on two counts," Perry wrote in a blog on the ASPCA website.
"First, at a time when Congress is cutting funds for education and other vital programs, it is outrageous that taxpayers would be asked to add $US5 million to the budget for something as senseless as horse slaughter.
"Second, since Americans don't eat horse meat, this action will only benefit foreign markets in Asia and Europe, where horse meat is considered a delicacy."
Congress, she argued, was clearly ignoring the will of the American people in allowing "our tax dollars to be used for this gratuitous cruelty".
"Though this setback is unfortunate, it signals the need for us to redouble our efforts for a complete ban on horse slaughter.
Perry noted that the slaughter ban in the US resulted in a sharp rise in the number of horses shipped to Canada and Mexico for slaughter.
She urged support for the American Horse Slaughter Prevention Act of 2011, which would not only ban horse slaughter in the US, but also ban the export of US horses to Canada and Mexico for slaughter.
"I encourage everyone who cares about horses to contact their federal legislators to press for passage of the American Horse Slaughter Prevention Act.
"Those in favor of horse slaughter are celebrating Congress's decision, and there's already talk of opening horse slaughterhouses in the Northwest.
"Given the controversial nature of this issue, it may be tough to find investors unwise enough to take such a leap knowing that we'll be working to defund horse slaughter again immediately.
"It is now more important than ever that Congress hears from horse advocates who know how essential it is that we protect these majestic animals."