Putting a Number on Pain: Quantifying and Recognising Pain in Equine Rehabilitation

Within the equine industry, horses continue to be stereotyped as naughty, grumpy, resistant, mean, or a typical mare when they are in reality showing signs of pain. It is our responsibility as equine rehabilitation practitioners to quantify and recognize pain in our equine patients, and to educate owners to recognize pain in their animals.

Many markers can be measured and used to quantify pain in the equine, the most valuable of these is behaviour. With advances in research allowing us to identify specific pain behaviours, we can now use composite pain scales in equines to quantify and monitor pain in our patients. This allows an objective method of measuring pain and its progression, improving communication and compliance between members of the multi-disciplinary team.

Let’s discuss some of the ways we can quantify pain.

Understanding equine pain

In this incredible companion and athlete, we are continually challenged not only to recognize pain – especially when the signs are subtle  – but to quantify and record the pain that a horse is experiencing.

The first hurdle is that pain is both sensory and emotional (Merskey & Bogduk, 1994). These two aspects need to be considered both separately and together, as we saw in a previous blog, where I looked at the relationship between pain and stress. Stress influences pain, and vice versa (Wagner, 2010).

The second hurdle is that the pain experience occurs as a result of real or potential tissue damage (Merskey & Bogduk,1994). Wow. How do we assess potential tissue damage? How do we quantify a horse’s experience of pain? Well, we could start by looking at some of the parameters that have been linked to pain through research.

Parameters that have been linked to equine pain

• An increase in heart rate and respiratory rate is easy to measure, record, and quantify. However, these values are non-specific and are of very little use on their own.
• Circulating levels of cortisol, catecholamines, and B-endorphins can be indicative of pain – but can also be an indication of high levels of stress. Again, these are of little value when taken on their own, and obtaining these measurements is not practical for the majority of us in the field.
• Pro-inflammatory mediators like prostaglandin E2, substance P, and bradykinin can indicate an inflammatory response, but again carry the restriction of being non-specific. These measurements cannot quantify the level of pain experienced and they are not available for us in the field.
• Changes in behaviour, including elements of demeanour, posture, gait, and interactive behaviour, whether subtle or overt, can be an accurate indicator of the presence, severity, and location of the pain. They may even give us indications of the chronicity of pain. Sounds like a winner to me, but the drawback is that assessing changes in behaviour means you may need a pre-pain behaviour assessment, as well as a great deal of time to get a handle on the full extent of behavioural changes.

These parameters don’t seem all that useful when we look at them like this, but the investigations into these parameters have led to something useful – the development of various pain scales.

As Vetrehabbers, palpation is our most relied-on assessment tool and outcome measure. We can become more objective in our use of palpation, which has been discussed in another blog. Pressure Algometry, likewise, can be a valuable addition to our assessments. You can read more about this tool here. 

Equine pain scales

For a pain scoring system – or a scale of any kind – to be of value to practitioners, it needs to be easy to use and relevant, the parameters need to be well defined and allow for repeated quick assessment by different observers with consistent results, it needs to be sensitive to different degrees of pain and specific to the kind of pain being assessed. That is quite a tall order.

These are some of the scales that are often used, and which may be of value to you:

• Visual Analogue Scales are simple horizontal lines, representing pain from none to the worst imaginable pain (we have all seen these in a doctor’s office or hospital). These are easy to use, but reliability and objectivity are questionable, becoming more unreliable towards the middle and lower spectrum of the pain scale (Grauw & Loon, 2016).
• Simple Descriptive Scales consist of pre-defined classes of pain to which numbers are allocated, as we see in our lameness grading systems (AAEP scale), and palpation scales.
• Numerical Rating Scales are horizontal lines with pre-set numbers from 0-10 at equal distances. An observer circles the number they feel is representative of the level of pain perceived (Grauw & Loon, 2016).
• Time Budget Scales look at behaviour over a period of time, allocating a time allowance for certain, specified activities. Due to the need for cameras and the time spent monitoring the animals, this is usually reserved for research settings (Grauw & Loon, 2016).
• Composite Pain Scales look at several pain-related parameters, including behavioural, emotional and physiological parameters, which are scored individually and then added together to provide an overall pain score (Grauw & Loon, 2016).

• Horse Grimace Scales focus on various facial features that changes in facial expression that have been shown to be associated with pain, allocating a point from 0-2 for each feature, and adding up to a total pain score.

• Behavioural assessment tools, like the Ridden Horse Pain Ethogram (RHpE), create a score for the occurrence of ridden behaviours that have been linked to the presence of pain. This is a useful measure to include for horses that are in work or returning to work within a rehabilitation program (Dyson, 2022).
• Movement assessment tools, like the Equine Quality of Movement Score (EQoMS) provide a structured method of assessing movement quality instead of only lameness. This again is highly valuable within rehabilitation and goes beyond a lameness scale (Bowen et al., 2025).  

The benefits of using pain assessment tools

If you are a fan of Dr Kenneth Joubert’s lectures, you will know that he is a big advocate of using pain scales in clinic, during assessments and during follow-up assessments. Pain scales allow clinicians to monitor a patient’s response to treatment over time, creating objective records that can be tracked from one consultation to the next. They also provide a simple way to communicate progress with owners. Even the simplest visual analogue scale completed weekly by an owner can become incredibly valuable when viewed over several weeks or months.

In canine hospital settings, pain scales are routinely used to monitor acute pain. In equine hospitals, they may be used following surgery and in painful conditions such as laminitis and colic, where validated composite pain scales have been developed. These tools help clinicians identify changes in pain and make informed decisions about ongoing management.

As rehabilitation professionals, however, we are often working with a different type of patient. Many of our patients are no longer experiencing acute pain, but instead present with subtle discomfort, altered movement, reduced performance, or compensation patterns. In these cases, assessment tools such as the Ridden Horse Pain Ethogram, and movement quality assessments like the Equine Quality of Movement Score can provide valuable additional information. While they each measure something slightly different, together they help us build a more complete picture of the horse, allowing us to monitor changes in pain, behaviour and function throughout rehabilitation.

No single assessment tool can tell us everything we need to know. The most meaningful clinical decisions come from combining validated outcome measures with a thorough physical examination, skilled observation and clinical reasoning.

To help you get started, I have included a downloadable Composite Pain Scale and Horse Grimace Scale below. If you would like to learn more about the Ridden Horse Pain Ethogram, you can download the official checklist from the Train with Trust Project. I would love to hear your thoughts and experiences using these assessment tools in practice, or whether this article has inspired you to start incorporating them into your own patient assessments.

References:

De Grauw, J.C. and Van Loon, J.P.A.M. Systematic pain assessment in horses, The Veterinary Journal 209 (2016) 14–22

Bowen, A.G., Tabor, G., Labens, R. & Randle, H. (2023). Visually assessing equine quality of movement: A survey to identify key movements and patient-specific measures. Animals, 13(18), 2822.

Bowen, A.G., Tabor, G., Labens, R. & Randle, H. (2025). Development of a grading system for visually assessing equine quality of movement. Journal of Equine Rehabilitation, 3, 100024. https://doi.org/10.1016/j.eqre.2025.100024

Bowen, A.G., Tabor, G., Labens, R., Douglas, M. & Randle, H. (2025). The Equine Quality of Movement Score: How reliable is it? Journal of Equine Rehabilitation, 3, 100023. https://doi.org/10.1016/j.eqre.2025.100023

Dyson, S., Berger, J., Ellis, A.D. & Mullard, J. (2018). Development of an ethogram for a pain scoring system in ridden horses and its application to determine the presence of musculoskeletal pain. Journal of Veterinary Behavior, 23, 47–57.