Pain, Behavioural or Both?
World Small Animal Veterinary Association Congress Proceedings, 2019
G. Pearson

Equine Hospital, University of Edinburgh, Edinburgh, UK


Horses often present to the veterinarian due to unwanted behaviours. These vary in severity from poor performance to dangerous behaviours including rearing and bucking when ridden. Owners also may request investigation if they perceive everyday scenarios such as girthing to elicit pain because of the horse’s behavioural response.

Objectives of the Presentation

This presentation will look at why various unwanted behaviours may occur and how they are reinforced. It will discuss how we can decipher if an unwanted behaviour is caused by pain, is primarily of behavioural origin or a combination of the two. Multiple video case studies will be used to demonstrate these points in the presentation.

How Behaviours are Reinforced

Behaviours can either be reinforced by the addition of something pleasant (positive reinforcement) or the removal of something aversive (negative reinforcement) immediately after the behaviour occurred. Ideally when the rider applies leg pressure the horse will move forwards (the desired behaviour) and the leg pressure is removed, thus rewarding the behaviour. However, if leg pressure is applied and the horse offers an unwanted behaviour (for example, bucking) and the rider’s leg moves as they lose balance, then then this removal of pressure will reward the unwanted behaviour (bucking). Horses will repeat behaviours that resulted in a release of pressure from the rider’s leg, rein contact or seat, even if the pressure is released for a fraction of a second. In this regard, horses will offer unwanted behaviours including bucking, rearing, napping/baulking and shying more and more frequently. It is important to recognize that the unwanted behaviour is not due to the horse being purposefully naughty but simply because it is being inadvertently reinforced.

Pain Resulting in Unwanted Behaviour

Obviously, pain or discomfort will motivate the horse to remove the source and can lead to the development of unwanted behaviours. A subtle, bilateral hind limb lameness may not be evident to the rider and trainer, but the discomfort may result in the horse being reluctant to push with its hind limbs and so instead poor performance is noted. Alternatively, the pain may be more marked when the horse strikes off in canter, and quickly the horse will associate pain with the transition.

Now when the rider asks for a canter, the horse will try and to avoid the transition, perhaps by ignoring increasing leg pressure or by offering an alternative behaviour such as bucking.

There are of course many causes of pain in horses, and in the presenter’s experience the majority of cases presenting with behavioural problems when ridden have some underlying physical reason. A thorough evaluation should include but is not restricted to:

  • Orthopedic assessment, both in a straight line and lunged on deep/hard surfaces by an experienced orthopedic clinician
  • Assessment of the horse’s back by both an experienced veterinarian and chartered physiotherapist, ideally to a chartered physiotherapist (UK) or sports medicine clinician. It should be remembered that generalized back pain is frequently a consequence of hind limb lameness
  • Full dental evaluation by an equine vet with extensive experience in dentistry
  • Gastroscopy (assessing both squamous and glandular portions)
  • Assessment of serum amyloid A can help to indicate if there is any inflammation ongoing (for example, an abdominal abscess) that would indicate further investigation such as abdominal ultrasonography

If no obvious source of pain is identified, it may be worth considering an analgesic trial. When undertaking an analgesic trial, especially in chronic cases, high doses may be required to see a significant difference. It is also important to remember that pain is a perception, whilst and while a positive response indicates pain as an underlying cause, a negative response to an analgesic trial does not rule out pain.

Any source of pain discovered should be taken seriously. Often veterinarians are aware of a low-grade lameness but do not think it is severe enough to justify the behaviour. As we have already mentioned, pain is a perception and an individual feeling; while one horse may be happy to continue doing its job with a marked lameness, others will not even tolerate a very subtle lameness without altering their behaviour.

Primary Behavioural Cases

Often when we perceive there are no underlying sources of pain, the underlying cause of the horse’s unwanted behavior actions is then assumed to be the horse’s behaviour, as if they are making a conscious decision to misbehave. Instead we should shift our focus to deficits in the horse’s training. We know what reinforces unwanted behaviours (i.e., that they are inadvertently reinforced through release of pressure when exhibited). So now we need to consider what might motivate a horse to trial unwanted behaviours in the first place. Most often it is a result of the rider/trainer not adhering to training principles that take into account the horse’s mental capacities and learning capabilities. Unwanted behaviours (rearing, bucking, shying, bolting, napping, etc.) are often called conflict behaviours and are trialed due to pain, fear or confusion in the horse’s training.

Training errors include:

  • Using contradicting aids simultaneously. This is probably the number one reason for horses to offer conflict behaviour. Consider that generally we train rein aids to elicit deceleration responses and leg aids to elicit acceleration responses. The problem occurs when the rider then attempts to influence the horses head and neck position by giving leg aids whilst holding onto a strong contact through the reins. It is understandable that the application of conflicting cues is very confusing for horses. They often initially trial opening the mouth to alleviate the increased rein pressure, hence an increase in the use of restrictive nosebands, and over time many become habituated to leg aids as the mouth is more sensitive. Ultimately many of these horses may then trial conflict behaviours to remove the conflicting pressures and of course any momentary release of rein or leg pressure if the rider momentarily loses balance will reward this behaviour.
  • Training more than one response per signal. Good training relies on distinctive cues for different responses. However, again some training methods use the cue of backwards pressure on the reins for deceleration but also use the same cue for flexion of the head and neck. For the horse it is difficult to understand when to offer which response and the resulting confusion may result in conflict behaviours being trialed.
  • Not training persistence of responses (self-carriage). If the horse is not trained to maintain its own speed, direction and line it will be constantly ‘practicing’ small unwanted behaviours. For example, if a horse constantly drifts to the left, they are practicing pushing sideways from their right foot without being asked. These horses are much more likely to spook sideways when startled (or even just randomly) as a bigger version of the smaller behaviour that has become habitual.
  • Not releasing the pressure. As we have discussed, horses learn through release of pressure. While horses habituate to the light pressures involved with contact, they are motivated to remove heavier pressures. As well as trying responses such as acceleration and deceleration, they may trial conflict behaviours through frustration of ‘not finding the right answer’.
  • Using too much pressure. Horses can be trained to respond to very light pressures. Consider a fly landing on a horse’s side; it swishes it tail because this removes the fly. Using excessive pressure from the rein or leg indicates that the pressure has not being removed at the right time in previous training. Horses find excessive pressure very aversive and are liable to trial conflict behaviours to remove it.

Equine veterinarians are of course not trainers; however, observing a horse that presents with unwanted behaviours being ridden can often give clues that poor training is contributing to the problem. The International Society for Equitation Science has published a poster and short document on the principles of training; the link is included in the reading list below.

Both Pain and Behaviour?

Often unwanted behaviours develop in response to pain. However, as the behaviour is repeatedly practiced a habit may form. In this scenario the behaviour may persist even when the pain has resolved. This is where retraining may be required alongside treatment of the physical condition and help from a qualified behaviourist is indicated.

Another interesting scenario is where no source of pain can be found and behavioural therapy is initiated. In the presenter’s experience, several of these cases have then gone on to demonstrate an obvious lameness in the following weeks or months. Although further research is required it is possible that these cases are in a state of increased sympathetic stimulation due to a combination of pain and confusion associated with poor training. Once the training level improves, the horses become more relaxed generally in life and then demonstrate lameness.

Summary Including Five Key “Take-Home” Points

1.  Deciphering if an unwanted behaviour is a result of pain, is a primary behavioural response or a combination of the two is very challenging.

2.  Workup of these cases requires lots of time and a team of people with expertise in different areas.

3.  Pain is almost always underlying in most cases presenting with unwanted behaviours when ridden.

4.  An analgesic trial indicates pain if a response is seen to treatment but does not rule out pain if no response is seen.

5.  Unwanted behaviours can develop as a consequence of poor training methodology, and observation of the horse being ridden can be useful to detect this.


1.  Pearson G. Practical application of equine learning theory, part 1. In Practice. 2015;37:5 251–254. doi:10.1136/inp.h2046.

2.  Pearson G. Practical application of equine learning theory, part 2. In Practice. 2015;37:6 286–292. doi:10.1136/inp.h2483.

3.  McGreevy P, McLean A. Equitation Science. West Sussex, UK: Wiley-Blackwell. IBSN 978-1-4051-8905-7.

4.  International Society for Equitation Science. The First Principles of Horse Training. (VIN editor: This link was modified on 9/2/20.)


Speaker Information
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G. Pearson
Equine Hospital
University of Edinburgh
Edinburgh, UK

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