Artificial Intelligence Could End Animal Suffering by Recognizing Pain

Scientists have figured out a way to understand the facial expressions of sheep using artificial intelligence, which they hope will help improve the welfare of sheep and other animals.

Researchers from the University of Cambridge developed a machine-learning technique to estimate the severity of a sheep’s pain using the Sheep Pain Facial Expression Scale (SPFES)—a tool used to assess pain based on facial expressions of the sheep.

The work built on earlier research into teaching computers to recognize human emotions and expressions.

“There’s been much more study over the years with people,” said Professor Peter Robinson, who led the research. “But a lot of the earlier work on the faces of animals was actually done by Darwin, who argued that all humans and many animals show emotion through remarkably similar behaviours, so we thought there would likely be crossover between animals and our work in human faces.”

artificial intelligence sheep AI pain cambridge How are ewe feeling? AI can determine whether a sheep is in pain through facial recognition. University of Cambridge

When a sheep is in pain, five things happen to its face, according to the expression scale: Their cheeks tighten, their ears fold forwards, their lips pull down and back, their nostrils change into a V shape and their eyes narrow.

A dataset of 500 photographs of sheep were used to train the model, with early tests suggesting it is capable of estimating pain levels with about 80 percent accuracy.

“The interesting part is that you can see a clear analogy between these actions in the sheep’s faces and similar facial actions in humans when they are in pain—there is a similarity in terms of the muscles in their faces and in our faces,” said co-author Dr Marwa Mahmoud.

“However, it is difficult to ‘normalize’ a sheep’s face in a machine learning model. A sheep’s face is totally different in profile than looking straight on, and you can’t really tell a sheep how to pose.”

The artificial intelligence system could eventually be used for early detection of conditions such as foot rot, which will allow for faster treatment and pain relief. By positioning a camera on a water trough or other area where sheep congregate, the researchers hope the system would be able to recognize any sheep that are in pain.

Join the Discussion