None of this pain ‘just disappeared’. Knowing I would need some help (I don’t function well and get very grumpy when I’m in pain), I booked in with my Osteopath asap. The first session went some way to easing the protective tension that had accumulated, but a subsequent threatening migraine necessitated another visit – leading to further improvement, and I’m hoping my third visit in a weeks’ time will do the trick. It’s now a month later, and I am still feeling the consequences of a silly slip.

What does this have to do with horses?  

Everything. I am lucky, in that I can recognise when I have an injury, vocalise where and what the pain is, avoid (hopefully) aggravating the issue, take pain relief if needed and, if I’m sensible, undertake some rehabilitative exercise to restore normal function. Horses have to rely on us to notice problems and provide appropriate actions.

The same day I fell over, I visited a horse for loss of performance. He was ‘feeling off’ in his right hind, showing occasional inconsistency in stride length, struggling with left canter transitions and had got very fussy/snatchy in the contact. As it turned out, he had fallen on the road about 6 weeks previous, not classed as a ‘bad’ fall – he spooked and slipped. Externally there were just a couple of grazes and he got up and carried on, apparently fine. He subsequently had a couple of weeks off (not fall-related), and just didn’t feel right when brought back into work.  

On observing previous video of him ridden, watching him in person, and eventually riding him myself, it became apparent that he had ‘lost connection’ from hind end to front. He was pulling himself along with the forehand and had become stiff in his lower neck, but over flexing the upper neck, causing compression and discomfort. Palpation revealed tension and rotation through the lumbar spine, lack of mobility on the left side of the pelvis and restriction throughout the neck and thoracic sling. So, that apparently innocuous fall had created a chain reaction of problems. He had been coping as best he could, but was having to adapt his biomechanics to protect the sore areas, resulting in altered balance and loading. Over time, this would lead to further performance issues, pain, overloading of soft tissues and joints and, eventually, injury.

Fortunately, his rider is skilled and intuitive, and recognised that the change in behaviour and way of going was likely a physical issue, so sought help. Now, alongside manual therapy to relieve the areas of spasm and restriction, he has returned to ground work and basic stability, strengthening and balance exercises specific to restoring equilibrium and correct function.

Firstly, the body is designed to stay upright, because – well, it wouldn’t be much good if it didn’t! Key to maintaining posture, balance and regulating eye position (which in a normal horse will maintain focus level with the horizon) is the vestibular system, centred in the inner ear and innervated by Cranial nerve VIII – the vestibulocochlear nerve. “The vestibular system is the primary sensory system that maintains the animal's balance, its normal orientation relative to the gravitational field of the earth. This orientation is maintained in the setting of linear or rotatory acceleration or deceleration or tilting of the animal. The vestibular system is responsible for maintaining the position of the eyes, neck, trunk, and limbs relative to the position or movement of the head at any time.” (1). So, if the vestibular system detects loss of balance, it signals the rest of the body to correct the abnormality. Inextricably linked to it, is proprioception. Proprioceptors are specialized nerves situated throughout the body that provide feedback to the CNS about posture and positioning and give the information required for correction of imbalance. Even the slightest disruption is instantly corrected automatically.

Secondly, muscle engagement. Efficient movement depends on synergistic coordination of more than 700 skeletal muscles. Deep postural muscles such as multifidi and longus colli serve to stabilise the spine, preventing excessive movement and allowing transmission of forces generated by the hind limbs to create forward movement. The abdominals also play a part in stability of the trunk. It has been shown in human studies that the nervous system pre-activates multifidi and transversus abdominus prior to limb movement (2), and research indicates the same activation patterns in horses (3).

So, when a horse falls, the Central Nervous System automatically tries to correct a sudden change in balance and directional forces. As a result, muscles contract to stabilise and keep the body the right way up, while gravity and momentum act conversely, putting strain on those shortened muscles.

The horse’s hind legs slip to one side. Immediately this causes torsion through the lumbosacral area. The lumbar spine is designed to have very little movement, but the lumbosacral junction (between lumbar spine and sacrum) has high flexion/extension mobility. Sudden, unusual movement commonly leads to pain and dysfunction, and the area also is a major compensation point for problems elsewhere in the body. The twisting continues forward through the thoracic spine, and the thoracic sling (musculature that suspends the ribcage and spine between the scapulae and front legs) cannot counteract the forces. While this is all happening, the vestibular system is frantically trying to keep the head orientation correct, so there is also rotation and lateral flexion of the neck as the horse falls sideways and impacts the ground.  

In this example, not only will you have bruising/lacerations from the impact, but potentially:

•  Strained, sprained or torn muscles. Muscles being recruited in the correct agonistic/antagonistic patterns will both create and withstand a wide range of motion, but those that are contracting against abnormal forces are susceptible to damage
• Vertebral compression or shearing due to the rotational and impact forces being exerted on the spine, particularly the cervical and lumbar area
• Rib cartilage damage, thoracic/rib cage rotation and disruption to function of the diaphragm

Any of these injuries will cause surrounding tissues to spasm in an attempt to protect, or ‘splint’ the damaged area. This will lead to loss of motion and asymmetry - as joints will be ‘stuck’ within a small range of their normal mobility - adaptive gait patterns, compensatory pain and eventually, further injury.

Wrong. It is well known that horses, even after thousands of years of domesticity, have a strong fight or flight response. To put it simply, if they don’t get up immediately, they get eaten by the closest predator. The endocrine system springs into action, releasing hormones including cortisol, which increases glucose metabolism to provide energy for escape, and adrenaline, which can help to mask pain. It is the desire to survive that also makes horses very good at hiding chronic (long term) pain or weaknesses. They will continue to do what is required of them, as my client’s horse was, to the best of their ability, but with compromised functionality.

Biomechanical adaptations made to accommodate injury, if not addressed, become ‘normal’ to muscles and proprioceptive feedback. Even if the initial pain is resolved, muscles that had ‘switched off’ to protect the injured area do not automatically switch back on again. As a result, they atrophy, or waste, and other areas have to try to take over their role. A common example of this is when horses suffer from pain of the long muscles in the back. It has been found that the deep multifidi – mentioned previously – can atrophy following injury, long-term weak posture or existing spinal pathology (4). This means that they are no longer being effective in their job of stabilising the spine, so the big locomotion muscles have to stiffen in order to prevent excessive motion in the spine, as well as creating movement.    

So, you then have a horse that is tight and sore under the saddle, and not performing as well as previously. A therapist could treat the back pain repeatedly, but unless the underlying cause (deep muscle atrophy) is addressed, the pain will not resolve. Over time, the compromised biomechanics leads to irreparably damaged ligaments and osseous changes, if they are not already present, to the joints and processes of the spine (spondylosis, osteoarthritis and ORDSP, or Kissing Spine). Note – there are numerous pathways of injury. This scenario is assuming the underlying muscle atrophy from a fall is the primary problem.  Fortunately, we know that specific exercises (with, or without the aid of electrotherapy) can re-activate atrophied muscles, and even reverse atrophy in those deep paraspinal muscles (5).  

1. If you have immediate concerns, call your vet. Prompt diagnosis and treatment of injury is essential and may significantly reduce recovery time and the likelihood of sub-clinical issues becoming long-term problems.
2. Call a reputable physiotherapist* as soon as possible. They will be able to assess for bruising, asymmetry and potentially abnormal gait patterns, which may be very subtle. They should also ask for details of how the horse fell, how it got up, how it reacted after the fall. This is all important information that could help determine potential problem areas. Prompt application of electrotherapies such as laser will also aid healing of superficial injuries.
3. Problems may not be apparent until several days or even weeks after the fall. Keep in contact with your physio, let them know of any changes in behaviour or way of going so that they can be addressed as they occur.
4. It is likely that specific rehabilitation will be required to correct movement dysfunction and/or asymmetry. Your physio will be able to advise you of appropriate exercises and if necessary provide a rehab programme. This will vary for each horse, and may need adjusting. Your horse may also need several musculoskeletal therapy sessions to help restore normal function.
5. STICK TO THE PROGRAMME! Rehabilitation can be a long process and can seem like you are getting nowhere at times. If you have any questions or worries, talk to your physio. They would rather spend a few minutes on the phone, than turn up at the next session to find that you stopped doing the exercises because * insert excuse here * and the horse is no further on in recovery. 

In my opinion, there is no such thing as a non-injury fall for horses – there will always be something that needs some help to recover. Often, you see jumping falls where the horse lands on its head and jack-knifes at the upper neck, or with its head and neck folded back under the body. Spoiler – these are the falls that break necks. However, even when momentum carries the horses weight forward and it rolls and gets back up, apparently unscathed, there will be serious soft tissue damage. There will be joint damage. We already see far too many cases of neck osteoarthritis – joint injury is a fast track to this condition. In a rotational fall, where the horses body comes crashing down – again, soft tissue damage, spinal and sacroiliac joint injury, pelvic fracture. Horses do get up from these falls, and quickly. They may be lame, but walk away in many cases.

This is not to open a debate whether horses should be used in sport. They can fall in the field. It is to raise awareness. I weigh well under 100kg and had a minor, relatively gentle fall – I’m functioning, but still dealing with the consequences a month later. On average, horses weigh anything between 400 and 800kg, and do not have the same degree of flexibility as we do. When they come down, it hurts. Do your bit to help them recover, and maximise the chance of long-term musculoskeletal soundness.

REFERENCES

(1) de LAHUNTA, A., & GLASS, E. (2009). Vestibular System: Special Proprioception. Veterinary Neuroanatomy and Clinical Neurology, 319–347

(2) BACK, W., CLAYTON, H.M. (2013). Equine Locomotion. 2nd Edition, Elsevier, China. p400, citing Hodges and Richardson, 1997, 1999; Hodges, et al, 2003b; Holm, et al, 2002; MacDonald, et al, 2010. 

(3) BACK, W., CLAYTON, H.M. (2013). Equine Locomotion. 2nd Edition, Elsevier, China. p400, citing Stubbs, et al, 2010

(4) STUBBS, et al,(2010). Osseous spinal pathology and epaxial muscle ultrasonography in Thoroughbred racehorses. Equine vet. J. (2010) 42 (Suppl. 38) 654-661

(5) STUBBS, N.C., KAISER, L.J., HAUPTMAN, J. and CLAYTON, H.M. (2011), Dynamic mobilisation exercises increase cross sectional area of musculus multifidus. Equine Veterinary Journal, 43: 522-529