But White Owl worries that if slaughterhouses open, owners will dump their unwanted animals there instead of looking for alternatives, such as animal sanctuaries.
Animal rights groups also argue that slaughtering is a messy, cruel process, and some say it would be kinder for owners to have their horses put to sleep by a veterinarian.
"Euthanasia has always been an option," Pacelle said. But "if you acquire a horse, you should be a responsible owner and provide lifetime care."
The fight over horse slaughtering has pitted lawmakers of the same party against each other.
Sen. Max Baucus, D-Mont., said the poor economy has resulted in "sad cases" of horse abandonment and neglect and lifting the ban will give Americans a shot at regaining lost jobs and making sure sick horses aren't abandoned or mistreated.
But U.S. Rep. Jim Moran, D-Va., is lobbying colleagues to permanently ban horse slaughter because he believes the process is inhumane.
"I am committed to doing everything in my power to prevent the resumption of horse slaughter and will force Congress to debate this important policy in an open, democratic manner at every opportunity," he said in a statement.