London, Aug 6 (IANS): Just like us, horses too can pucker their lips or raise their chins to convey important messages, new research shows.

They use muscles underlying various facial features - including their nostrils, lips and eyes - to alter their facial expressions.

The researchers identified in horses 17 discrete facial expressions many of which are similar to humans.

"Horses are predominantly visual animals, with eyesight that is better than domestic cats and dogs, yet their use of facial expressions has been largely overlooked,” said the study's co-lead author Jennifer Wathan, doctoral researcher at the University of Sussex in England.

"What surprised us was the rich repertoire of complex facial movements in horses, and how many of them are similar to humans,” Wathan noted.

"Despite the differences in face structure between horses and humans, we were able to identify some similar expressions in relation to movements of the lips and eyes,” she said.

The findings suggest evolutionary parallels in different species in how the face is used for communication.

The researchers analysed video footage of a wide range of naturally occurring horse behaviour to identify all the different movements it is possible for horses to make with their face.

They also carried out an anatomical investigation of the facial muscles that underpin these movements. Each individual facial movement that was identified was given a code.

Horses share some surprisingly similar facial expressions to humans and chimps, showed the findings published in the journal PLOS ONE.