Kissing Spines

Another pain in the back

by Emiliano Espinar, MRCVS

The spine position within the body and the number of vertebrae of each section

You would only expect to get the best results after putting all the joy and hard work into training, wouldn't you?

Well, sometimes things don't quite go to plan! We may face a tendon injury or in other cases we may want to look for another physical problem that might explain why a horse is not jumping or performing as expected. Back problems can certainly be one of them. After all horses are not designed to have riders on their backs.

Back problems can be a major cause of poor performance, for some disciplines or breeds more than others.

Quite commonly riders and owners alike would seek advice from paraprofessionals and/or veterinarians on possible back problems. In reality back pain can be challenging to diagnose and therefore to treat. But why is it so difficult to diagnose?

The back is a large area with deep muscle padding hiding the bony structures - also the complexity of the great number of structures that involve the back mean that it can be difficult to isolate individual reactions to back pain.

Diagnosis should no longer be a “guessing game”. Thanks to the great advances in the last few years, we now have the means to establish a definitive diagnosis.

These are some of the common problems we see with back pain:

  • Poor performance.
  • Not making proper shape whilst jumping.
  • Inability to perform a dressage manoeuvre that it normally does (i.e. resisting collection or lateral movement).
  • Hates to be rugged or groomed.
  • Muscle atrophy in certain areas.
  • Difficult with farrier.

But how can we tell?

The manifestation can be variable, from “the performance has deteriorated” to “dangerous when ridden”.

On many occasions, it is brought to the attention by a therapy paraprofessional during a routine maintenance treatment.

Symptoms are not always specific and/ or difficult to prove. To complicate matters, there could be other causes (i.e. stomach ulcers, hormonal problems that may contribute).

In reality, when it comes to “difficult behaviour”, horses are very honest and more often than not there is a physical/ physiological explanation rather than a pre-meditated behaviour to avoid work.

How can we diagnose back problems?

Not every horse with a “sensitive back” has to have a primary back problem. In fact, more often than not we can blame the cause on limb lameness, typically bilateral hind limb lameness. The challenge is not only demonstrating the presence for example of “kissing spines”, but to confirm that they are causing a problem.

A careful inspection can highlight areas of asymmetry or muscle wastage as an indication of back abnormalities.

Clinical examination is most important and a normal horse would be expected to have a pain free range of spinal motion both in dorso-flexion and latero-flexion. Stiffness of the back, even in the absence of palpable pain, can indicate problems as some horses guard themselves “like a plank of wood” to avoid manipulation.

Horses should be examined from the ground and it is very important they are also ridden.

When horses are trotted in hand (more so in slow trot) the back relaxes and bounces up and down when pain free, therefore this is the best pace to assess back suppleness. When ridden they generally struggle to maintain a threebeat canter, become disunited or show signs of discomfort.

Causes of primary pain

  • Impingement of the dorsal spinous process, more commonly known as
    kissing spine
  • Articular process arthropathy or facet joint arthropathy
  • Sacroiliac disease
  • Kyphosis (upward curvature), lordosis (downward curvature) or scoliosis
    (sideways curvature) of the spine.
  • Spondylosis, which is a degenerative disease of vertebrae
  • Azoturia, or tying up
  • Muscle strain
  • Stress fractures of the pelvis, ribs, sacrum etc.

Causes of secondary pain

  • Girth galls
  • An ill-fitting saddle
  • An ill-fitting bridle or bit, or one that is inappropriate for the horse
  • Dental issues
  • Lameness of the hind or fore limbs
  • Lack of fitness, a sporadic training regime or occasional, extreme amounts
    of exercise.


There are useful tests, such as the ‘surcingle test’ where the pressure of the surcingle can dramatically change their action and therefore give some indication of back pain. However beware that this test can have a dangerous reaction in some horses with severe back pain (or sometimes stomach ulcers).

“Kissing spines” also known as “Impinging dorsal spinous processes” or “overriding dorsal spinous processes” (ODSP), are always high on the list when it comes to back pain. They are generally associated with unrideable horses and this can certainly be the case. However other horses may well be competing at the highest level and coping well with them.

There are many factors that may make this condition more active and painful and every individual could have a different presentation. In fact some horses, typically with very chronic “kissing spines” where the spines are almost fused, may just show back stiffness and may present with hindlimb lameness (i.e. suspensory pain) as the limbs will work harder to compensate for the lack of back mobility.

Also the temperament and how ‘sensitive’ they are to pain has proven to be another factor.

Musculature, other than serving as a cushion for the saddle, holds the spine and is vital in injury prevention. Muscles run through the length of the spine and connect throughout the length of the vertebrae, which is why it is not surprising that kissing spines can be related to or mimic clinical presentation of lumbo-sacral or sacroiliac pain.

The most practical diagnostic tests are X-rays (i.e. see picture right demonstrating the presence of kissing spines), which generally can be done at the yard. Ultrasound can also be useful to further look at the soft tissue involvement. There are other hospital diagnostic tools such as a Bone Scan that can be helpful but they may not actually be that reliable in more chronic ongoing problems. Thermography can complement in some cases, but it is not indicated as a diagnostic tool.

Ultimately we can confirm that there is a problem by ‘blocking’ the horses back. The back would be injected in the affected areas with local anaesthetic and if it is the source of pain, the horse improves under a rider (unfortunately only for a few hours). The response to this test can help us to decide a more effective treatment.

Are all horses prone to Kissing Spines?

Not really; there is a genetic predisposition and some horses can have kissing spines before having weight on their backs. Horses with high withers/short backs would be more predisposed to have kissing spines. Horse with long backs are not immune and they have more predisposition towards ligament/soft tissue injuries of the back. Some horses will develop deformation of the spines when they start to be ridden at a young age.

So this combination of genetic and early weight stress on the back can be evident in breeds such as racing thoroughbreds where the incidence of back problems is very high.

How do we treat them?

We always encourage a more conservative treatment as the first plan of action, in an attempt to avoid surgery. In fact there could be great results with rehabilitation and re-schooling with an experienced rider. The exercise program should encourage the development of a top line and abdominal muscles to protect the back from strains. A combination of changes such as rider, saddle and physiotherapy can keep things on track.

At this stage horses could be treated (i.e. steroid injections, mesotherapy, etc) to control pain and muscle spasm.

If the problem can not be managed successfully, surgery could be the next step. Surgery has improved vastly in the last few years. It was originally done in the 80’s under GA (with an increased risk of death and bleeding). Currently they are done standing under sedation.

Fact: Conformation can play a role; horses with a combination of high wither-short back are predisposed to kissing spines. Horses with long backs are more predisposed to soft tissue injuries.

There are several techniques that are recommended depending on the

individual case:

  • Interspinous ligament desmotomy (ISLD). A minimally invasive procedure which consists of cutting the ligaments between the affected spinal processes in the hope of relieving pressure. Horses are back in work between 6 to 8 weeks. The surgery will, I believe, de-nerve the painful areas and I have seen some horses presenting secondary fractures of small fragment edges of the spinal processes without any clinical signs!
  • Conventional surgery involves dissecting portions of upper spinal processes to allow space. This may have a longer recovery period (6 months approx.), however it is a more long-term treatment.

The prognosis of surgery is variable. As a guidance, at least 60% would improve after surgery, 30% may not change and 10% may actually get worse!

In conclusion, interpretation of back pain requires a holistic approach and successful management often involves the vet, physiotherapist and controlled exercise regimes/rehabilitation.

Palpation of the back

Horses react differently to palpation. We generally assess reactions to both superficial and deep palpation. Some horses are just ticklish and very reactive. In any case, it is surprisingly easy to ask a horse to extend and to flex the back using the right pressure points. To test sideways movement we put pressure on the opposite croup at the same time as we press the near side to achieve a left flexion and vice versa. Make sure you don't stand behind!

It can be normal, however, for the horse to mildly resist these movements. The point of this is to assess the ability of the horse to flex his spine. Repeat this on the other side.

To test flexion we can pinch the skin under the sternum and for extension we can firmly apply finger pressure at both sides of the spine under the saddle area (pictures below).

Horses should have a good range of motion. Any lack of movement or unusual response could potentially be suspicious.

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