At least two stolen dogs were found in an operating room used for dissections at the medical school of South America's oldest university but its dean has denied hiring dognappers to collect specimens for classes.

Peru's University of San Marcos does not have access to enough human cadavers for its students, so they sometimes cut open dogs instead.

Carmen Valverde's dog Tomas was stolen by two men while she was walking in the working-class Brena district of Lima and a friend who works at the school's teaching hospital spotted him by chance in a surgery room where dogs are dissected.

Ms Valverde donned a lab coat and snuck into the hospital to rescue Tomas.

Video her friend shot a week ago, aired on local television, shows the dog sedated, splayed, and strapped to a stainless steel table moments away from the knife.

After local newspapers published the story, other people with missing dogs rushed to the hospital's door and one owner found her dog, Chico.

"The University of San Marcos still hasn't apologised for what it has done," Ms Valverde said.

Ricardo Rubios, dean of the medical school, acknowledged that stolen dogs had wound up in the surgery room but he said the school only uses strays for classes.

"I assure you we would have returned the dog," he said. "All our experimental surgeries are done to dogs that don't have owners."

Romila Briones, a member of ASPPA, a Peruvian animal rights group, said the law does not protect strays.

"In Europe, they don't kill animals for education, they use dummies," she said. "Unfortunately, animals are just property in the eyes of the law here, like furniture."

- Reuters