Engagement and Kissing Spines:

How are they Related?

In this column, I have been discussing the importance of engagement and how it is achieved.  Interestingly, engagement is also directly related to the condition of kissing spines.  Kissing spines refers to the condition where the dorsal spinous processes of two or more adjacent vertebrae are abnormally close to one another and may actually rub against one another. While there are cases of horses being born with this condition, it is thought that the vast majority of cases develop later in life.  So what would cause this condition to develop? There are a variety of theories as to what causes kissing spines ranging from a traumatic incident,  conformational issues, unbalanced shoeing situations, poor riding technique, to consistent use of a badly fitting saddle.  

I would like to discuss the development of kissing spines from a chiropractic perspective.  The vast majority of kissing spines are found in the region of the anti-clinal vertebra, typically recognized as T16.  At this site, the angulation of the dorsal spinous processes changes from facing forward (behind T16), to facing towards the back end of the horse (forward of T16). 

The T16 vetebrae is indicated with arrow.

This area lies directly under where the rider usually sits when riding the horse.  There is a significant amount of force exerted in this area both from the rider and from the anatomical situation of the change in direction of the dorsal spinous processes.  The anti-clinal vertebrae is the least stable of the surrounding vertebrae due to this increase in force.  It is thought that a hypermobility (increase in mobility) develops at this site with a resultant drop in the back in this area, moving the dorsal spinous processes closer together and the development of kissing spines.  The body's response to the hypermobility is an effort to stabilize the area, which frequently results in what is chiropractically termed a vertebral subluxation complex.  Simply put, this is a restriction to the mobility of the vertebral joint.  So it starts with a hyper (or increased) mobility and leads to a restriction in mobility. 

So how do we address this problem?  Many times, it is recommended that the back be strengthened.  With a little thought as to the biomechanics of the area, it will be apparent that this is exactly the opposite of what needs to be strengthened.  What really needs to happen is that the back needs to lift in this area.  How is this accomplished?  Remember our discussion of the bow and string description of engagement?   In order to lift the back and open up the space between the kissing spines the abdominals need to be strengthened.  In proper engagement, the abdominals contract and the spine flexes or lifts.  If the system is working properly, when the spine extends (or sinks down), the mechanoreceptors in this area should be activated and send the signal for the muscles that make up the abdominal 'string' to contract and flex the spine up appropriately.  If there is a restriction to the mobility of of the vertebral joint in this area (in chiropractic terms, a vertebral subluxation complex), then the spine doesn't extend, the supporting muscles don't stretch, and the abdominal 'string' muscles are not fired, they don't contract, there is no engagement, and the back doesn't flex and the vertebrae remain pushed together as kissing spines. While kissing spines are frequently treated with anti-inflammatories (which can be an important component of the overall therapeutic plan) and back strengthening exercises, it is now easy to see that it is essential that the horse be evaluated for any restrictions to the motion of the vertebrae in this area.  If the vertebral subluxation complexes in this area are not corrected, the horse will not be able to properly contract the abdominals and will not be able to achieve proper engagement, and there will be no hope of opening up the space between the affected dorsal spinous processes.  It is important to dig deep into the reasons why an abnormal condition has developed and not just treat the symptoms if we hope to have a lasting successful outcome.  

Based on this knowledge, my treatment protocol for kissing spines includes a combination of chiropractic evaluation and appropriate adjustments along with shockwave therapy, and a regime of abdominal strengthening groundwork exercises.  The chiropractic adjustments will help to facilitate the horse's ability to achieve proper engagement, and the shockwave therapy will help to decrease the inflammation and pain associated with the condition, specifically the pain that may be felt on dorsal (upward) flexion of the  spine.  This combination of treatments will enable the horse to more effectively work in exercises designed to strengthen the abdominal muscles which will in turn aid the horse to dorsi-flex the spine and hopefully open the spaces between the dorsal spinous processes. I recommend Hilary Clayton and Narelle Stubbs' book and DVD:  Activate Your Horse's Core:  Unmounted Exercises for Dynamic Strength, Mobility, and Balance.   This is an excellent and very specific resource from a recognized expert in the field of gait analysis and equine biomechanics. The incorporation of these exercises into the treatment and management program for a horse with kissing spines is essential.

This combination of chiropractic adjustments, shockwave therapy, and appropriate exercise will help to facilitate the strengthening of the abdominals that is essential to strengthen the abdominal 'string' portion of the bow and string model of engagement in the horse. The treatment of kissing spines frequently requires a multi-modal approach and the success rate can be quite variable, as can the clinical signs associated with kissing spines.  It is also important to have a thorough diagnostic evaluation, potentially including a variety of imaging, to make sure that there are not additional underlying problems that could be clouding the diagnostic picture.