Hartpury College

Kissing Spine Surgery


Injuries and diseases of the back are a common cause of poor performance in sport horses (Jeffcott, 1980). Back pain tends to cause a decrease in range of movement i.e. an increase in stiffness of the back. Back pain may arise from any tissue within the back and can be quite difficult to diagnose as horses vary in their responses to back pain and in the way that they cope with it. Presenting signs could include everything from subtle changes in gait and performance right through to resistance to work including aggression on being saddled, bucking, inability to canter, refusal to jump etc.


The vertebral column of the horse is made up of up of 5 different regions (cervical, thoracic, lumbar, sacral, coccygeal) with different types of vertebrae in each region. Within the thoracolumbar spine, the vertebral bodies have dorsal spinous processes (DSPs) projecting from them for the attachment of soft tissue structures (tendon, ligament and muscle). Between adjacent vertebrae, a gap of 4 mm or more is considered normal (Zimmerman et al. 2012). If adjacent DSPs are touching they are considered to be ‘impinging’; if adjacent spinous processes are overlapping they would be considered to be ‘over-riding’. Both impinging and over-riding dorsal spinous processes (ORDSPs) otherwise known as kissing spines are a common cause of back pain in horses (Jeffcott 1980). In the worst affected cases adjacent DSP’s will show signs of change in bone density (sclerosis) and/or bone breakdown (radiolucencies on x-ray).


During the normal stride cycle, the back flexes (rounds) and extends (dips). The interspinous gaps narrow when the horse’s back is extended and increase when the back is flexed. The exact aetiology is unknown, but it has been suggested that horses with short backs, excessively extended backs (due to their conformation), horses subject to repetitive flexion-extension movements (e.g. jumping horses) or horses with an extended back posture due to concurrent hindlimb lameness or carrying excessive weight may be predisposed to the condition. Single or multiple DSPs may be involved. Diagnosis may be made on the basis of presenting signs, response to palpation, local analgesia, ultrasonography, radiography and nuclear scintigraphy (Zimmerman et al. 2012). Often multiple diagnostic techniques are used to confirm the diagnosis. Presence of ORDSPs on a radiograph may not correlate with the clinical signs, in other words horses with evidence of ORDSPs on x-ray may not exhibit signs of pain arising from that region; another horse may have only mild impingement but exhibit signs of significant pain.


Treatment can be conservative (i.e. rest, physical therapy and anti-inflammatory medication) or surgical. In some circumstances additional complementary therapy such as acupuncture may be used to decrease spasm of the muscles surrounding the painful vertebrae (see video). Surgical treatments are resection of DSPs under general anaesthetic, resection under standing sedation or interspinous ligment desmotomy which is carried out under standing sedation (Coomer et al. 2012). Comment [KN1]: Insert video of Fiona doing acupuncture. Outcomes may be improved in both instances by the use of physical therapy within the recovery period. Rehabilitation programmes are from 3 to 6 months (Walmsley et al. 2002). Physiotherapy is recommended post-surgery (Walmsley et al. 2002).



Show jumper (competing at 1.50 m level) suffering from poor performance (knocking down fences, often with hind limbs)

Diagnosis: ORDSPS with 3 intervertebral joints affected (T17-18, T18-L1 and L1-L2) (see x ray)



Treatment:  Interspinous  ligament  desmotomy  which  was  carried  out  by  Chris  Rea BVM&S, MRCVS at Three Counties Equine Hospital. The horse was then referred to Liz  Launder,  osteopath  for treatment  at  the  Equine Therapy  Centre,  Hartpury College.

Rehabilitation: 12 weeks

First 2 weeks: Box rest with in hand walking/grazing only. Sutures removed day 10. The  horse  begins  a  programme  of  electrotherapy  (ultrasound  and  interferential treatment)  as  prescribed  by  Liz.  (see  pictures  of  the  therapeutic  ultrasound  and interferential machines).

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Work commences 2 weeks post surgery with controlled walking on ordinary treadmill (no incline).

3  weeks  post  surgery:  Walking  up  to  45  mins  per  day  (in  2  bouts  consisting  of  1 treadmill session  and one ground schooling session in  long lines  with short periods of trot). Both osteopath and vet feel that the amount of propulsion from the hindlimbs could be improved by modifications to the shoeing and at the next appointment, Liz, Chris and Kelvin Lymer of Sandpitt Forge all see the horse together to discuss what can  be  achieved with  shoeing. Kelvin  uses  a  shoe  with greater  length  and  width  to provide  a  larger  bearing  surface  to  the  hindlimbs  and  ‘derotate’  the  hindlimbs. Currently some of the drive is lost because the hindlimb (particularly the right hind) is overly outwardly rotated and isn’t able to push forward sufficiently, instead it tends to lands towards the midline which is increasing the amount of axial rotation along the spinal  column  (we  want  flexion  of,  and  propulsion  along  the  longitudinal  axis,  not around  it). (see the photo showing the new shoe on the right hind with the old shoe laying  on  top  of  it.  This  shows  how  much  more  support  the  new  shoe  gives  in comparison)

6   weeks   post   surgery:   Introduce   canter   during   ground   schooling.   The   horse underwent   osteopathic   mobilisation   under   sedation   to   improve   the   range   of movement of the caudal thoracic and lumbar spine. (see video).

10 weeks to 12 weeks: Cantering and jumping (under 1 m) with rider. 



Kissing Spine Surgery
1. Find out the key differences in structure of cervic al, thoracic, lumbar and sacral vertebrae.
2.Think about which muscles would make the horse’s back extend (dip) and flex (round)?
3.Where is the greatest range of flexion-extension within the horse’s back?
4.What do the following terms mean:
5.Find out how nuclear scintigraphy can aid the diagnosis of kissing spines.