Facial Expression

Definitions:

Oxford Reference:

What does this look like?

Why does this happen?

Understanding Stress and LIMA

Training

Sources:

Definitions:

Oxford Reference:

Facial Expression: Non-verbal communication using the muscles in the face

Dalla Costa, et al., 2014 (2):

'Action units': individual or a combination of facial muscles contracting
- ex) raising an eyebrow

What does this look like?

A newer concept in the horse world that you may or may not have heard of the equine pain or grimace face. Scientists and behaviorists have been working over the past decade or so to map out the different facial expressions of horses (1, 2). As it turns out, horses have a number of facial markers that we can analyze to determine a horse's mental state, both good and bad. Below is a diagram of facial expressions ranging from relaxed (a) to in pain/discomfort (1).

Activity: Analyze the diagram below and list the differences in each expression.

Current research has allowed us to identify and map the specific facial markers that change to form an overall expression, modeled after research in humans, mice, rabbits, and dogs (1, 2, 3, 4, 5, 6)! Research in other species over the decades has laid the groundwork for equine scientists to develop the Facial Action Coding System (FACS) for horses. You may be familiar with the markers discussed below already, but there are a couple of markers that are often overlooked. Ears, eyes, lips, nose, and cheeks all work together to form the expression, so it is important to look at all aspects of the face and not focus on just one part over others.

Below is an example of an objective scoring chart to analyze a horse's pain/grimace face before and after castration (2).

Here is another example of an equine pain face from the same horse in different contexts. Note the minor differences in ear, lip, and nose positions that all play a role in the overall expression.

Ears: Many people have heard of the terms "happy ears" and "angry ears," but often the in between positions are misunderstood. In this example, the ears are in very similar positions between discomfort and relaxation. The picture on the left shows them slightly further back than the picture on the right.
Eyes: The picture on the left shows the horse's eye more open and "peaked" at the brow. This is sometimes called a "tent" because of the triangle shape it makes. This eye shape is a classic sign of pain/discomfort/stress. The picture on the right shows a more relaxed eye with no "peaking" or "tenting".
Nose: The nostrils shown in the left picture are noticeably tense and flared. The opening is larger and the nostril seems to come away from the muzzle a bit from the tension. The nostril on the right is smoother, smaller, and relaxed.
Mouth: The lips in the left picture show some tension, which you can see with the lower lip pulled in and tight, causing a "beak"-like mouth shape. On the right, the lips are even and smooth, showing more relaxation than on the left.

As you can see, we need to look at the whole picture to figure out how the horse might be feeling!

Why does this happen?

Facial expressions are a normal way for animals to communicate, but we must be able to notice when a horse is showing signs of discomfort. Below are a few examples of identified horse facial expressions (7):

Pain faces can be seen in any horse, no matter the discipline or training method or even training level, and it has been seen as a normal part of training. However, plenty of horses compete and exercise without showing those signs of pain. The two sets of pictures below show horses in exercise or competition with different expressions. Some mild signs of stress will be expected during exercise, much like a human will show some tension during exercise, but signs of pain as seen below should be addressed immediately.