One of the keys to successful treatment of medical issues in the horse is early detection of the problem. Horses evolved over millions of years as prey animals who are reluctant to show pain or weakness. As such, we often have problems recognizing low grade pain in the horse and assessing response to treatment objectively. Facial expression in mammals involves voluntary and involuntary muscles. Such an automated machine learning project may also open the road for automated recognition of pain in a number of other relevant species, including cattle, dogs, swine and rodents.