The war between animal activists and the Pentagon has raged for decades. You could say there’s been a fair amount of collateral damage: thousands of goats and pigs have been mutilated, though the military argues the animals have not died in vain.

So it’s no surprise the animal rights camp is salivating over the blow it’s about to inflict on the enemy. This week, by order of Congress, the Pentagon must present lawmakers with a written plan to phase out “live tissue training,” military speak for slaying animals to teach combat medics how to treat severed limbs and gunshot wounds.

The demand, tucked into the National Defense Authorization Act of 2013, marks the first time Congress has ordered the Pentagon to provide a detailed plan to start relying less on animals and more on simulators. The military must also specify whether removing animals from training sessions could lead to a “reduction in the competency of combat medical personnel,” according to the bill.

“Congress now acknowledges that it is wrong to harm animals for crude medical training exercises if modern and superior alternatives are available,” said Justin Goodman, the director of laboratory investigations for People for the Ethical Treatment of Animals, or PETA, which has been fighting the use of animals in combat medic training since the early 1980s. “If the military is too entrenched to make changes on their own, Congress is going to bring pressure to bear and force that change.”

The military’s use of animals for medical training dates back to the Vietnam war, but it drew relatively little scrutiny until the summer of 1983, when activists caught wind of a training exercise planned at a facility in Bethesda. The plan to shoot dozens of anesthetized dogs strung on nylon mesh slings in an indoor, sound-proof firing range enraged animal activists and some lawmakers.

Dog lovers protested in front of the Uniformed Services University of the Health Sciences, one with a leashed dog wearing a shirt with a bull’s eye. They took their rage to the home of then Defense Secretary Caspar Weinberger, demanding to know how he could stand for the training as the owner of an adorable collie named Kilty.

Weinberger acted swiftly, issuing a one-sentence statement saying he had “directed that no dogs be shot for medical experimentation or training.” But to the consternation of animal activists, Weinberger did nothing to spare goats.

The military was not alone in using animals to prepare medics for trauma. Thomas Poulton, a Texas anesthesiologist who served in the U.S. Navy Medical Corps , said many civilian trauma training courses used dogs when he was a young physician three decades ago. He found wounding animals during courses jarring, but not particularly formative.

“In terms of actually learning skills, eye-hand coordination or learning much intellectually, it didn’t really add anything I wasn’t already learning,” said Poulton.

In recent years, civilian trauma courses have largely abandoned the use of animals, chiefly because human simulators have come a long way, spurting blood-like liquid and reacting much like the human body when it’s wounded. Poulton says civilian schools have ditched live-tissue training in part due to ethical concerns.

“There’s a creepiness factor for many people,” he said. “These were healthy dogs from the pounds and healthy farm animals.”

Michael Bailey, a former Army combat medic who served two tours in Iraq, disagrees. He first went to Iraq after taking basic courses that did not include treating wounded animals. He had the doctrine down. But when Bailey first treated a casualty in the northern city of Kirkuk after an artillery attack, he froze.

“This guy in front of me is missing a leg,” said Bailey, who writes a blog called the Madness of the Combat Medic. “I went blank. I was like, woah. It took someone asking me what to do for me to snap out of it.”

He later took a more advanced course in which he and two other medics treated a sedated goat’s bleeding femoral artery after the instructor slashed it without warning. Bailey said the mannequins used in that training course were extraordinarily effective. But the goat exercise provided a sense of urgency that only real life trauma can provide.

“You don’t get that feeling from a mannequin,” he said. “You don’t get that feeling of this mannequin is going to die. When you’re talking about keeping someone alive when physics and the enemy have done their best to do the opposite, it’s the kind of training that you want to have in your back pocket.”

Pentagon officials have made that argument for decades, emphasizing that combat medics need unique, specialized training.

“The use of live animals in medical training teaches warfighters to save lives on the battlefield,” Pentagon spokeswoman Jennifer D. Elzea said in a statement. “Comprehensive combat medic training is vitally important because the medic is the first responder who provides treatment to an injured service member or civilian.”

PETA scored two tactical victories last year. After polling all NATO nations, Goodman and other investigators determined that only six of the 28 members of the alliance use animals in combat medic training. Britain is among those that use animals, but its trainees are sent to Denmark because using live animals for medical training is not permitted in Britain.

More strikingly, the animal advocacy group got a leaked video of a Coast Guard combat medical training exercise that featured an instructor whistling as he severed a goat’s limbs with tree trimmers. The disclosure triggered a federal investigation into allegations that the animals had not been properly anesthetized. Members of Congress sent a letter to the Pentagon expressing concern. Elzea said the Pentagon has revised training modules over the year to “provide more oversight.” The company was cited for violations of the federal animal welfare Act.

The congressional mandate does not compel the military to abandon animal training altogether. And it’s clear the armed forces aren’t keen to. The Army recently announced a $5 million contract bid for goats to use at combat medic training facilities across the country over the next five years. The solicitation baffled PETA because work for the contract is scheduled to start March 1, the same day the Pentagon’s report to congress is due.

“This is a case of the real world and the political world colliding,” said Bailey, 29, the former Army medic. Because the military is about to enter a period of peace, he predicted, “the real world is going to lose out.”