Pigs have been long used in medical schools to teach surgical techniques and, more recently, in research trials and experimental xenotransplantation procedures. But given the rise of alternative simulation technology and mounting pressure from animal rights groups and lawmakers, animal labs for medical training have become less common.

Just last month, the Physicians Committee for Responsible Medicine (PCRM), a nonprofit group with a decades-long stance against the use of animals in medical education and research, placed billboards around the Portland, Oregon, area demanding that Oregon Health and Science University (OHSU) stop using pigs to teach surgical residents.

Dr John Pippin

Undergraduate medical programs no longer use live animals. But a small number of graduate medical education programs still use animals, predominantly pigs, to train physicians in subspecialties like internal medicine, emergency medicine, surgery, and anesthesiology, John Pippin, MD, FACC, director of academic affairs at PCRM, told Medscape.

Pippin says residents practice establishing emergency airways, inserting chest tubes, and accessing blood vessels on anesthetized pigs before euthanizing them.  

Swine lab advocates say pigs make ideal training subjects because of their similarities to humans, including comparably sized organs like the heart, lungs, and kidneys. Pigs share about 85% of their DNA with people. Where pig skin alternatives may suffice for less invasive procedures, supporters say residents’ experiences with live tissue are irreplaceable.    

In a statement, Sara Hottman, associate director of media relations at OHSU, told Medscape the school “only uses animal models in its surgical training program when non-animal methods are inadequate or too dangerous for human participants.”

“We believe that the education and experience surgical trainees gain through the use of relevant animal models are essential to ensuring future surgeons have the knowledge and skills necessary to provide safe, high-quality care.”

Hottman also noted that the university continues to evaluate alternatives and looks forward to when non-animal “surgical training methods are capable of faithfully modeling the complexity of a living system,” such as in the management of critical internal complications.

But Pippin argues that residents can gain sufficient expertise through simulators and hands-on training in the operating room, and that the differences between humans and pigs are too vast to provide meaningful clinical data or skills.  

“Pigs have different genetic influences and very thick, tough skin,” he said. If you use the same pressure on a human that you learned on a pig, he added, “you’d slice right through the trachea. Whatever you think you find out in animals, you have to learn all over again with humans.”

Undergraduate medical education programs in the United States and Canada abandoned the practice of using live animals, including pigs, by 2016, with Johns Hopkins University School of Medicine, Baltimore, Maryland, and the University of Tennessee College of Medicine in Chattanooga the last to announce their shift away from the controversial teaching model following campaigns by PCRM.  

Today, most residency training programs have followed suit. Pippin said that pediatric residencies no longer use animals, and all trauma and anesthesiology programs have ceased such practices except two. Just 3% of emergency medicine programs continue to use animals, as do about 21% of surgical residencies, he said, based on PCRM’s latest surveys.

A Public Debate

Occasionally, PCRM goes public with a campaign against a residency program “if that’s the only way to win,” Pippin said.

In addition to billboards, the group has held protests, circulated petitions, and filed complaints with the US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS), the entity responsible for overseeing the health and welfare of animals used in medical training and research.

In 2021, spurred by a complaint from PCRM, APHIS launched an investigation into the University of Cincinnati’s, Cincinnati, Ohio, surgical residency program. At the time, a university spokesperson acknowledged the school’s limited use of pigs to train “highly-skilled, well-prepared surgeons in the most advanced, complex, real-world needs, procedures and techniques,” adding that the training methods were endorsed by the American College of Surgeons and in compliance with federal guidelines.

Residency programs have caught the attention of state lawmakers, too. In 2020, bills introduced in both the Rhode Island House and Senate sought to ban the use of live animals in medical training when “there is an alternate teaching method that teaches the medical procedure or lesson without the use of an animal.” Violators would incur misdemeanor charges and monetary fines of up to $1000 per animal.

The bills — backed by PCRM — targeted Brown University’s, Providence, Rhode Island, emergency medicine residency program, which sponsoring legislators said was the last program in New England still using the “outdated” and “unnecessary” method.

In testimony before lawmakers, the school said fewer than 15 pigs participate in the annual training, and faculty spoke about the benefits of the experience.

“If it was your brother or sister, or your mother or father who had to come in and get this procedure done, would you want the physician who’s doing it to be the one who does it for the very first time on a human being, on live tissue? Or do you want that provider to have only practiced on plastic and rubber?” said Nicholas Musisca, MD, an assistant program director with Brown University’s emergency medicine residency, NBC affiliate WJAR reported.

The bills have since stalled, and PCRM held a protest at Brown University in October 2022. In response, a university spokesperson told The Brown Daily Herald, “effective synthetic model alternatives simply do not exist for every complex medical procedure that an emergency physician must be prepared to perform,” including establishing an airway in adult and pediatric patients with severe facial trauma.

By the Numbers

Annual reports from APHIS do not show the number of pigs dedicated solely to residency training. Instead, reporting indicates the number of animals “upon which experiments, teaching, research, surgery, or tests were conducted involving accompanying pain or distress to the animals and for which appropriate anesthetic, analgesic, or tranquilizing drugs were used.”

For fiscal year 2021 — the most recent data available — OHSU had 154 pigs under its control, while the University of Cincinnati (UC) and Brown University had 118 and 71 pigs, respectively, according to APHIS. Primates were more commonly used at OHSU and guinea pigs at UC.

Similarly, the Association of American Medical Colleges supports the “use of animals to meet essential educational objectives [across] the medical education continuum.…Further restrictions on the use of animals in biomedical and behavioral research and education threatens progress in healthcare and disease prevention.”

The debate will likely rage on. “The one thing we don’t do is give up,” Pippin said.

Steph Weber is a Midwest-based freelance journalist specializing in healthcare and law.

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