They may look placid while grazing in fields but sheep's faces can tell us a lot, according to scientists in Britain who have developed a new system to work out if sheep are in pain or just feeling sad.
The test is based on 500 photos of sheep collected by veterinarians and used to design an algorithm by researchers at Cambridge University that measures five key markers of ovine facial expressions.When sheep are in pain their eyes narrow, their cheeks tighten, their ears fold forwards, their lips pull down and back and their nostrils change from a U shape to a V shape, according to the scientists.
They now hope to extend the test to other species, including horses, rabbits and some rodents.
By installing cameras in sheep pens, the scientists hope the test will help farmers spot injuries or illnesses early on and find treatment.
"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," Peter Robinson, a professor who led the research, said in a statement.
His colleague Marwa Mahmoud said: "There is a similarity in terms of the muscles in their faces and in our faces.
"However, it is difficult to 'normalise' 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 scientists are now hoping to perfect the system by enlarging their dataset and the project seems to be having a personal effect.
"I do a lot of walking in the countryside and after working on this project, I now often find myself stopping to talk to the sheep and make sure they're happy," Robinson said.
