LOS ANGELES — A federal judge gave the green light for horse slaughter to resume in the United States, perhaps as early as this week.

In issuing her ruling late Friday, U.S. District Judge Christina Armijo, who is based in Albuquerque, dismissed a lawsuit by animal welfare groups that had sought to prevent such slaughter.

Front Range Equine Rescue, the Humane Society of the United States and other animal rights groups contend that federal officials didn’t perform appropriate studies before granting permits to Valley Meat Co. in New Mexico and a company in Iowa.

Armijo also denied a permanent injunction that would have blocked Valley Meat Co. from reopening its Roswell, N.M., slaughterhouse to horses.

A. Blair Dunn, attorney for Valley Meat Co. and Rain Natural Meats in Missouri, said both companies plan to resume operations as soon as next week. The companies want to export the horse meat for human or animal consumption.

“We are pleased,” Dunn said. “We think the right legal conclusion was reached.”

The Humane Society promised to appeal Friday’s ruling, stating that it was just the latest legal battle over the treatment of horses in the American West.

“With today’s court ruling and the very real prospect of plants resuming barbaric killing of horses for their meat in the states, we expect the American public to recognize the urgency of the situation and to demand that Congress take action,” Wayne Pacelle, president and chief executive of the organization, said in a written statement.

The issue of horse slaughter has proved to be divisive with a heated debate over what is the most humane solution to the nation’s overpopulation of horses, with many of the animals neglected and starving.