Researchers in New Zealand secured live pigs to a surgical table and shot them in the head with a pistol as part of a study into blood-spatter patterns.
An animal rights group said they acted cruelly, and urged them to end such experiments.
But the government-funded Institute of Environmental Science and Research said the pigs were sedated and treated humanely.
The scientists say their analysis is important in understanding human shooting deaths.
The study was published in July in the International Journal of Legal Medicine. It describes how five pigs were shot from close range with a Glock semi-automatic handgun to record the back-spatter of blood, bone and brain material.
Justin Goodman, from the group People for the Ethical Treatment of Animals, said the experiment was unnecessary.