PORTLAND, Ore. (KOIN) — Animal rights organization PETA has launched a scathing campaign against an Oregon university that allows obstetrics and gynecology students to perform surgery on pigs as a part of their training.

The animal advocates say that Oregon Health & Science University’s OB/GYN residents have conducted invasive procedures on up to 48 live female pigs “despite vast anatomical differences between humans and pigs.”

According to PETA, OHSU’s usage of animal testing makes it an outlier in the U.S. An ongoing survey from the organization found that institutions like the University of North Carolina and the University of Washington have opted out of animal testing for OB/GYN training programs for years.

The nonprofit also says medical centers at the University of Texas, Rush University and Aurora Sinai have all switched to human-like surgery simulators since receiving guidance from the organization.

“Pigs feel pain as we do, but they’re anatomically different animals who aren’t stand-ins for women,” PETA Vice President Shalin Gala said in a statement. “PETA is calling on OHSU to stop killing pigs and switch to the advanced, highly realistic simulators found in nearly every other accredited OB/GYN program.”

The organization claims that it has directly reached out to OHSU about its training practices, but officials haven’t responded.

To catch the attention of the university and its students, PETA has placed a billboard on West Burnside Street and Southwest Third Avenue that reads, “Oregon, don’t train doctors to think women are really pigs!”

OHSU officials told KOIN 6 that its OB/GYN program only uses animals as subjects when non-animal testing would be inadequate or harmful for human subjects. The university says animal models are anesthetized and monitored by veterinarians during training.

“We look forward to a time when nonanimal surgical training methods are capable of faithfully modeling the complexity of a living system,” OHSU spokesperson Sara Hottman said. “However, technology currently does not exist to recreate some of the most complex procedures surgeons must regularly perform in humans.”

Additionally, OHSU says it will adopt non-animal training techniques when they are scientifically approved.