Evaluating horses' pain

Source: uu.nl
Horses cannot tell us whether or where they hurt. Moreover, as horses are prey animals, their instinct dictates that they not allow their pain to show. Because it can be important to learn about what they are feeling, a pain scale for horses has been developed. In Utrecht.
Thijs van Loon of the Utrecht University Equine Clinic, in collaboration with other researchers, has accepted the challenge of developing a pain scale for horses. A number of physiological parameters has been examined, such as rectal temperature, respiration rate and bowel sounds. Beyond these, the team has observed specific behaviours such as restlessness, sweating, kicking the belly, scratching, muscle tremors, poor appetite, and aggression and/or decreased response in interactions with humans. Together these parameters make up the pain scale. Yet, just as with humans, horses’ reactions to pain are not all alike. The pain scale is not 100% accurate, but it does provide a good snapshot of a horse’s comfort level.

The scale has been tested on 48 horses that required emergency surgery for colic. Horses with higher pain scale scores had a greater risk of complications that make a second surgery necessary, or even euthanasia. According to Van Loon, this pain scale is but a first step in research on equine expression of pain. The investigator hopes that further research will yield scales for specific pains.