Equine Conditions – Kissing Spines
Dorsal spinous process (DSP) impingement also known as Kissing Spines is the most common cause of back pain in horses (Coomer, 2013; Jeffcott, 1980).
Looking at the anatomy of the horse’s spine helps understanding of this condition (see Fig 1). The horse’s spine is divided into 5 regions:
Each of these sections has a number of vertebrae that are different shapes depending on their location and role. There are:
- 7 cervical vertebrae
- 18 thoracic vertebrae
- 6 lumbar vertebrae
- 5 sacral vertebrae
- 15-25 caudal (coccygeal) vertebrae
The thoracic, lumbar and sacral vertebrae have dorsal spinous processes for muscle attachment, the thoracic vertebrae have the tallest spines (DSPs) which should have equal spacing between them. In horses with kissing spines there is a narrowing of this space in mild cases progressing to the spines touching or even overlapping or fusing causing pain in severe cases (Fig 2)
The area most commonly affected in the thoracic region, under the saddle (T11-18) but it does occur in other areas of the spine.
It has been found that 39% of horses have kissing spines (Turner, 2011) but many of these do not display signs and are clinically normal (Erichsen et al., 2003). Symptoms of kissing spines range in severity from loss of performance to extreme behavioural issues (Zimmerman et al., 2012).
Diagnosis is normally a combination of symptoms displayed, reduced spinal movement, X-Ray and/or scintigraphy.
There are several treatment options available, the least invasive and usually attempted first is rest and physiotherapy depending on the extent of the symptoms. The next (more common) step is steroid injections into the interspinous spaces affected to control pain and inflammation usually alongside physiotherapy to assist pain management and reduce muscle spasm (Walmsley et al., 2002). If these methods are not successful or do not last long term the next step is surgery.
There are 2 main surgical procedures commonly available, DSP resection and interspinous ligament desmotomy (ISLD). DSP resection involves the removal of the summits of the affected (touching or close) DSPs. This surgery is invasive with a prolonged rehabilitation time of around 6 months (Coomer, 2013). ISLD is less invasive with similar success rates and reduced rehabilitation time (6 weeks) (Coomer et al., 2012, Coomer, 2013).
DSP resection aims to recreate space in the spine to remove pain and ISLD aims to relieve tension on the nerve endings found at the ligament insertion to remove the sensation of pain. This combined with controlled exercise and physiotherapy to release muscle spasm resolves KS permanently (Coomer et al., 2012).
Lameness is also often associated with KS (Zimmerman et al, 2011) due to the lack of muscle surrounding the spine caused by back pain. This muscle loss reduces core stability which effects spinal movement and causes gait adaptations in an attempt to relieve the pain (Bromiley, 2009). These compensations can lead to both forelimb and hindlimb lameness issues including foot related lameness, tendon/ligament and sacroiliac issues (Coomer, 2012). Zimmerman et al., (2012) found that some horses have developed a coping strategy in association with either forelimb or hindlimb lameness (often mild and bilateral) becoming progressively stiffer and more restricted in their movement.
Research suggests that allowing horses with overriding or impinging DSPs time out of work is detrimental due to links between the lack of spinal musculature and KS.
There is research to support the use of core strengthening exercises in horses to help maintain strength and mobility which is not only beneficial for horses with KS but also as a preventative measure and for general wellbeing, strength and suppleness. Stubbs et al., (2011) found that regular use of baited stretches increases the size of the multifidus muscle which is a spinal stabilizer. If you have any concerns about your horse, you should consult your Veterinary Surgeon.
The equine athlete needs to learn to use his muscles for mobility but also for stability. The muscles that support the spine and abdomen need to be recruited to enable the core to support itself which allows the limbs to function correctly without the extra burden of an ill supported core.
There are numerous simple exercises that can be done daily (5 times a week) to assist in building core strength.
Baited stretches are good for horses that are not too food obsessed and likely bite! Make sure that your horse is stood on a non-slip surface. Stretches should be held for around 5 seconds and repeated 3-5 times (* – both ways)
- chin to chest
- chin to knees
- chin to fetlocks
- chin to shoulder (*)
- chin to outside of knee (*)
- chin to outside of fetlock (*)
Tail pulls are another simple exercise to improve core strength targeting abdominals and pelvis stabilisers. Ensure that the horse is stood on a non-slip surface, grasp the tail gently but firmly towards the base of the dock and gently pull in the desired direction, be careful not to pull the horse off balance you are aiming to see the abdominal muscles contract without moving the horse. When releasing the strain do not let go of the tail, gently release the pressure to allow the horse to return to it’s natural balance. Hold for 5 seconds, repeat 3-5 times.
- Tail pull to the left
- Tail pull to right
Another simple exercise than can be added into your existing routine is transitions, as many as you can do – on your way to/from the field, out hacking and of course when schooling. Adding these simple exercises to your routine can help make your horse stronger, more supple and agile and reduce wear and tear on the limbs!
Bromiley, M. Rehabilitation. In: Equine Back Pathology: Diagnosis and Treatment. 1st Edition. Oxford, UK. Blackwell Publishing Ltd 249-261
Coomer, R.P.C. McKane, S.A. Smith, Vanderweerd, J.E. 2012. A Controlled Study Evaluating a Novel Surgical Treatment for Kissing Spines in Standing Sedated Horses. Veterinary Surgery. 41 890-897
Coomer, R. 2013. New Surgery for Kissing Spines. Veterinary Times. 43 (21) 20-21
Erichson, C. Eskell, P. Wistrom, C. Roethlisberger Holm, K. Johnson, C. 2003. Scintigraphic Evaluation of the Thoracic Spine in the Asymptomatic Riding Horse. Veterinary Radiology and Ultrasound. 44 330-338
Jeffcott, L.B. 1980. Disorders of Thoracolumbar Spine of the Horse: A Survey of 433 Cases. Equine Veterinary Journal. 12 197-210
Turner, T.A. 2011. Overriding Spinous Processes (Kissing Spines) in Horses: Diagnosis, Treatment and Outcome in 212 Cases. AAEP Proceedings 57 424-430
Stubbs, N.C. Hauptman, J. Clayton, H.M. 2011. Dynamic Mobilisation Exercises Increase Cross Sectional Area of Musculus Multifidus. Equine Veterinary Journal. 40 (1) 14-20
Walmsley, J.P. Petterson, H. Winberg, F. McEvoy, F. 2002. Impingement of the Dorsal Spinous Processes in 215 Horses: Case Selection, Surgical Technique and Results. Equine Veterinary Journal. 34 23-28
Zimmerman, M. Dyson, S. Murray, R. 2012. Close, Impinging and Overriding Spinous Processes in the Thoracolumbar Spine: The Relationship between Radiological and Scintigraphic Findings and Clinical Signs. Equine Veterinary Journal. 44 178-184