Congress had been unable to pass legislation banning slaughter despite polls indicating that 70 per cent of Americans were against the trade, the umbrella group for anti-slaughter groups said.
"When it comes to stopping the slaughter of horses, clearly money talks," spokesman John Holland said.
Equine welfare advocates have been trying since 2001 to get Congress to pass legislation to ban the slaughter of American horses.
"Polls have consistently shown that the legislation has the support of 70 per cent of Americans, but without fail the bills have been stalled, blocked with secret holds, and left off the legislative calendars. Now it appears the EU and Canada may stop horse slaughter before Congress," Holland said.
Strict new traceability requirements will go into effect from July 31 for all horses slaughtered for consumption in the EU.
The EU is poised to require Country of Origin labeling of all meat and the alliance says the EU has also begun investigating inhumane slaughter practices in Mexico.
"The agricultural special interests have continually been allowed to prevent the legislation from moving forward," Holland said.
This was despite US President Barack Obama's promise to not allow lobbyists to run the country and his support of a horse slaughter ban when he was in the Senate, Holland noted.
Legislation was recently introduced to the Canadian Parliament to ban horse slaughter for human consumption, "threatening to accomplish what our Congress should have done years ago".
"It is an embarrassment the EU has to enforce drug policies because our Congress won't stop the flow of untraceable horses that put the health of European consumers of horse meat at risk," Holland said.
"Moreover, it is a further embarrassment that, despite an unending stream of gruesome undercover videos, our Congress continues to allow American Horses to be brutalised.
"The abuse and cruelty inherent with horse slaughter is well known to our Congressional members. The horrific findings of the recent investigations into Canadian and Mexican plants did not reveal anything that wasn't prevalent in US plants before their closure in 2007."
A Government Accountability Office report in 2004 revealed improper stunning of equines before slaughter. A follow-up to the report noted no improvement and a 900-page US Department of Agriculture report documented serious transport injuries.
"Yet," Holland noted, "the brutal practice was allowed to continue."