In their sights are the American Veterinary Medical Association (AVMA) and the American Quarter Horse Association (AQHA).
The anti-slaughter lobby has succeeded in getting the three abattoirs that slaughtered horses for human consumption shut down.
However, they are concerned that federal law still allows the shipping of horses across the borders into Mexico and Canada for slaughter.
Cruel slaughter practices have been exposed in Mexico.
They are seeking a federal law change to not only outlaw slaughter, but prevent American horses being shipped beyond its borders for slaughter.
Organiser John Holland said it was time the anti-slaughter movement went on the offensive.
He accused pro-slaughter advocates of setting up phony "welfare" organisations and using the offices of organisations such as the AVMA and the AQHA to "project an agenda that has no motivation but greed".
"Since their position has no morally acceptable justification, they simply create one.
"Most recently they are getting third-rate reporters to pump out completely fabricated stories like the ones about horses being abandoned around the country.
"Having produced this documentary 'proof', they trolled the darkest recesses of the bowels of congress to find someone who would have no problem with propagating their poison. The most recent denizen to emerge to their beckoning calls was Senator Larry Craig."
Senator Craig, he said, had stained the Senate floor with objections based on "stories so rank that no self respecting dead fish would be found wrapped in them".
Mr Holland said playing defense had no upside and was merely damage control.
"We must be ready to counter this detritus, but that alone is not enough."
He accused the AVMA and AQHA of hypocrisy and deceit. "We must take the battle to them on ground they think safe."
Anne Russek, the director of media relations for the Virginia Equine Council, described the American Quarter Horse Association as one of the main suppliers to and supporters of the horse slaughter industry and one of the main opponents to the American Horse Slaughter Prevention Act (AHSPA).
"Pro-horse slaughter organisations such as the American Quarter Horse Association have been working hard to mislead Congress and employ underhanded tactics to block the will of the majority of Congress and the American people," she said.
"While the AQHA argues it opposes the AHSPA because there is a so-called 'unwanted horse problem' it is the main producer of foals in the US - with tens of thousands of new registrations every year - and is actively promoting the mass breeding of more foals.
"This irresponsible breeding programme rewards the bottom feeders of the horse industry such as killer buyers and assorted auction racketeers."
The AQHA, she argued, was more concerned about protecting "hefty profits" obtained by certain mass breeders through slaughter and "keeping pace with several anti-animal agribusiness lobby groups".
The council has organised a campaign in which it asks anti-slaughter supporters to contact NBC's Oklahoma City affiliate KFOR to objects to its intended broadcasting of the AQHA's World Championship Reining Show on January 12.
She also urged lobbyists to contact the station's headquarters in New York to lodge similar objections.
John Holland said the AVMA can expect to feel heat, too, from the anti-slaughter movement.
"When we are done, no veterinarian will want the AVMA decal to deface his or her door," he said.
"None of this will change our ongoing work on Congress. That has become a well oiled machine. It is simply a matter of making these organisations realize they will find us pulling back the covers in everything they do."