—Sarah, Westborough, Massachusetts
A.Judging the level of pain or discomfort a horse experiences can be a challenge for anybody. We have to rely on behavioral signs that differ among horses and change across situations. Responses to pain include active behavioral indicators (such as ear-pinning, flank-biting, and lameness), or suppression of behavior; stoic horses fall into this latter group. This lack of expression could indicate a higher tolerance, but suppressing signs of pain might also reflect an evolved survival strategy in prey animals, including horses, because it hides vulnerability in the presence of predators1.
The horse can reveal pain, fear, irritation, and contentment through its body language. Some aspects of these emotional states are involuntary and impossible for even the most stoic horse to suppress.
A horse’s eyes are a window to its emotions. When a horse experiences distress or pain, the pupils dilate or constrict, and the eye changes shape. A relaxed horse has a round, soft eye, but when in pain the eyelids might close and the orbital crest bones become exposed and prominent2. The eye takes on yet a different shape when a horse experiences stress or fear—it becomes triangular, and wrinkles form above the eye; the greater the number and depth of wrinkles, the more stressed the horse is likely to be3.
Other Facial Indicators2
Horses experiencing pain might hold tension in the jaw and clench or grind their teeth. Tension above the mouth causes the upper lip to draw back, creating the appearance of a pronounced “chin.” The horse’s nostrils become rigid and dilated. The horse might also hold its ears stiffly to the side or back, giving the appearance that they are set widely apart.
Some horses react to annoying or aversive stimuli with learned defensive behaviors (avoidance, escape, and aggression), but a withdrawn body posture is more widely recognized as an indicator of pain. The withdrawn horse4 has a low head carriage, with the neck horizontal to the ground rather than rounded. It has a rigid stance and fixed gaze, head position, and ear position.
Changes in Activity Level
Expressive horses might become restless, irritable, anxious, or aggressive when they experience pain, but stoic horses, and those with chronic or severe pain, typically become less active and more isolated. They are often indifferent or slow to respond to events going on around them, have a loss of appetite, and show changes in sleep patterns—especially if laying down is impaired by the pain.
Horses with low emotional expressivity have experiences that are more intense than their body language reveals. Your horse is fortunate to have an owner who cares about how he is feeling, because it can be easy to miss or brush off the stoic horse’s subtle signs of pain, discomfort, fear, or even happiness. Becoming familiar with your horse’s typical behavior will help you recognize changes in facial expression, body posture, and activity levels that signal pain or discomfort.
Remember: Contact your veterinarian if your horse shows signs of severe or chronic pain that might be associated with an injury or illness requiring medical attention.
- 1Ashley, FH, Waterman-Pearson, AE, and Whay, HR (2005). Behavioural assessment of pain in horses and donkeys: application to clinical practice and future studies. Equine Vet J 37, 565-575.
- 2Bailey, A. (2015). When I look into your eyes: what eye wrinkles in horses tell us about their emotional state. ISES Media Release.
- 3Costa, ED, Minero, M, Lebelt, D, Stucke, D, Canali, E, and Leach, MC. (2014). Development of the horse grimace scale (HGS) as a pain assessment tool in horses undergoing routine castration. PLOS One 9(3): e92281.doi:10.1371/journal.pone.0092281
- 4Fureix, C, Jego, P, Henry, S, Lansade, L, and Hausberge, M. (2012) Towards an ethological animal model of depression? A study on horses. PLOS One 7(6): e39280. doi: 10.1371/journal.pone.0039280.