Many horse wonders and equine professionals will have come across a horse with the diagnosis of “Kissing Spines” but despite the widespread occurrence, there appears to be considerable confusion and conflicting information around causative factors and the management of the condition.
Here I aim to demystify the condition and provide a clearer understanding of what is actually occurring, why it may have developed and how to manage it. As with any of our articles on animal pathologies, all advice and information given is a guide only and all animals presenting with illness, lameness, or veterinary emergencies must be seen by a qualified Vet.
What is Kissing Spines?
Kissing Spines can have a number of presentations depending on the spinal level affected, the bone development present and the impact on surrounding tissues. The term “Kissing Spines” come from the radiological finding of the dorsal spinous processes touching or even overriding one another with osteophyte development known as Baastrup’s sign (Filippiadis et al., 2015). Depending on the type of finding, it may sometimes be referred to as Impinging Spinous Process (ISP) or Over Riding Spinous Process (ORSP).
The condition could occur at any age but the most common range is between 5 to 10 years old (Hill, 2018). Commonly, the location of the spinous processes approximating is in the low thoracic region, which is clearly often affected by the weight of the saddle and rider.
However, there may be cases where the location of dysfunction is more cranial or caudal, which will depend on a range of factors. The lower region of the thoracic spine is also where the angle of the dorsal processes change, making it more likely for impingement to occur (Young, 2019).
The horse has long pronounced thoracic spinous processes that act as attachment sites for strong muscle groups and connective tissues supporting the forelimb and their longnecks. On radiography and dissection, these spinous processes can appear fragile and fracture can occur with falls, particularly at the withers where they are at their longest.
While the equine spine does have movement in all ranges, the degrees of motion are limited compared to some other quadrupeds, such as dogs and cats (Jean-Marie Denoix, 2019). This natural development of a sturdy spine is the feature that has made them so good for riding.
By considering Osteopathic philosophy here, we can see that adding the weight of a rider and tack, created an allostatic load on the body. While breeding specific traits into our horses can attempt to improve their vital reserve to support this extra weight bearing, the fact still remains that without correct conditioning, posture and capable riding, the load may not be supported without detrimental changes occurring.
Causes and Maintaining Factors
Each animal is an individual and so the situations that led to them presenting with kissing spines will be equally unique. Many factors, however, will be common among affected horses. Some of the factors include:
- Posture
- Conformation
- Fitness and condition
- Age
- Riding - Training level and rider ability
- Tack fit
Horses with conformation that predisposes them to kissing spines may be long-backed and have developed sway back posture, creating excessive extension of the spine. If a horse is not regularly in work and lacks muscular condition, they may not have the abdominal strength to support a neutral spine with the added weight of a rider.
A younger horse who has not been trained to a higher level of schooling may not have the coordination or self-carriage to avoid hyperextension (hollowing). Rider ability can heavily affect a horse's way of going as well as riders who are too heavy for the horse. Should a saddle be positioned incorrectly or too long for the horse, this can place the rider's weight in a position more difficult to support
While, as with any condition, there may be some genetic predisposition, Kissing Spines research is ongoing. Research in recent years has made progress on identifying genetic links.
A study published in the December 2022 is of, Research in Veterinary Science journal found that a region on Chromosome 25 “increased the average grade of kissing spines by one for each copy of the chromosome, called an allele, with the mutation. For each of the horse’s two copies of the allele (one from each parent), the data indicates an average increase in one severity grade of kissing spines, thus confirming the link between genetics and the severity of the disease.”
However, we can consider that certain breed commonalities may impact the ongoing sporting/riding development of the horse.
Some horse breeds that display more upright confirmation in the head and neck may more naturally “hollow” their back during movement. It is important that all training of horses considers their unique physiology and essential that steps are taken to provide support to body structures that are already predisposed to spinal extension.
Popular driven breeds such as Hackney, Gelderlander and Welsh Section D can show higher natural head carriage, as can the American Saddlebred. These breeds shouldn't be made to move in a way that is not conducive to their conformation, but there should be sufficient conditioning in their training to engage spinal flexion and isometric strength.
The current thinking is that there are both heritable and non-heritable factors that influence the development of Kissing Spines.
Bone Changes Kissing Spines
The development of bone changes, including bone spurs, callus and malformation, is described in Wolff's Law. The bone tissue will alter in shape depending on the forces placed upon it (Rowe, Koller and Sharma, 2023).
The spongy cancellous bone will become more dense and strong and the cortical bone layer will strengthen and thicken too. Unfortunately, this bone change can create ongoing problems and worsen symptoms in the case of kissing spines.
As the spinal processes make contact, the pressure applied stimulates bone callus and overgrowth to occur. This change is actually the body attempting to protect itself and reduce the excess movement that is creating dysfunction. However, once this change has occurred, the bone spurs (osteophytes) and enlargements can irritate the surrounding tissues, and of course, by altering structure, function is altered too.
Once radiological findings show excessive bone growth at the site of kissing spines, Vets may opt for surgery to reduce the growths. This is clearly a much more invasive process than some other earlier interventions, and so early diagnosis and intervention is most sought.
This process is known as an Osteotomy, in which space is created between portions of the spinous processes that overlap by ‘bone shaving’, which can reduce pain. This procedure will vary in its impact and recovery time depending on the severity of the condition and the location of the surgery. Vets may suggest this surgery even in retired horses and horses not in work, as the bone changes can impact the horse’s natural healthy behaviours such as rolling, laying down and social interaction.
Another more modern surgical procedure that may be performed is inter-spinous ligament desmotomy (ISLD). In this surgery, vets will locate the point of the infringement and cut the inter-spinous ligament between the affected dorsal spinous processes. This is with the aim of reducing pressure and creating space. It is also less invasive than Osteotomy and is done while the horse has standing sedation as opposed to full anesthesia. It is less expensive and has a faster recovery time than Osteotomy.
Management and Osteopathy
Clearly, prevention of a condition is far better than cure. In the early stages of kissing spines, the signs can be very mild or not even shown at all. Many horse owners and trainers may mistake the signs for something else less severe, or even dismiss them as bad behaviour.
Types of behaviours include:
- Reluctance to move forward under saddle
- Cold backed when mounting
- Bucking
- Napping
- Rearing
- Aggressive or pain behaviour when girthing up
- Head shaking
- Tail swishing
This is by no means an exhaustive list of signs. Some signs might just be noticed when grooming, such as muscle spasm when brushing their back. The key is to remember that any sign your horse shows that is not normal for them, when they are fully happy and healthy, should be checked out.
Regular Osteopathic treatment can help to highlight these signs and your Osteopath can then refer back to the Vet to get a diagnosis. An Osteopath can use their palpatory skills and clinical assessment to investigate the early signs of kissing spines that might not be noticed by the owner, such as: Spinal restriction, tenderness on palpation, muscular fasciculation, gait disturbances, unevenness, postural asymmetries.
Prevention and conservative treatment often look exactly the same. While the Vet might consider giving steroid injections at the affected area to reduce inflammation and pain, the rest of the work is very much a daily management process. Importantly, the management routine must be conducted within the horse’s abilities at the time, graduation of exercises and gentle progression will be more successful than rushing the process.
Owner care Kissing Spines
Owners can be directed by their Osteopath and Vet to use exercise and care tips to treat kissing spines. This can include:
- A formal routine of progressive exercise
- Groundwork to encourage conditioning without rider weight
- Poles (ground and raised poles) - this encourages abdominal engagement and spinal flexion to improve spinal control
- Stretching exercises - usually focused on spinal flexion and perhaps lateral flexion to gap the approximated tissues
- Sometimes heat pads and rugging advice might be given in colder months
- Nutritional advice to manage weight and its impact on the spine - also useful during conditioning to ensure adequate protein and energy intake
- Tack fitting and use education
Osteopaths Kissing Spines Care
The Osteopath will use their understanding of the horse’s entire lifestyle and routine to come up with a care plan that aims to remove blockages to health while also dealing with potential initial causes.
The Osteopath will often work with the owner’s trainer, saddler and other professionals to combine ideas and ensure continuity in the care plan.
Direct interventions the Osteopath may employ include:
- Manual mobilisation of the spine and peripheral joints
- Soft tissue therapy/massage to relieve pain and improve function
- Core engagement techniques
- Spinal manipulation
- Some Osteopaths may also be trained in the use of electrotherapies such as shockwave and pulsed electromagnetic field therapy
Indirect interventions the Osteopath may employ could be:
- Exercise planning
- Rehabilitation plans
- Turnout and stabling routine advice
- Feed and hay positioning - lower to encourage flexion
- Owner care advice, such as simple massage techniques and stretching
Conclusion
The pathophysiology of kissing spines is predominantly one of mechanical strain and eventual loss of painless function. There may be compounding factors to the development of the condition such as systemic health problems that could lead to muscle weakness and loss of condition; conformational faults and postural abnormalities causing predisposed spinal extension.
However due to the mainly mechanical nature of this issue, the best form of intervention is education around the biomechanics of the spine and how to monitor factors that place excessive strain on the horse.
Riders should always be aware of their position, training level and of course their weight. Talking to riders about their weight can be a difficult subject but it is imperative to maintain their horse’s health. There is much to be gained from having all tack fitted properly by a qualified individual who will be able to recognise any signs of pain and could even recommend tack additions and adjustments that could help during the rehabilitation phase.
It is evident from the current research into kissing spines that conservative and preventative care are most recommended by the veterinary profession due to the surgical approaches being highly invasive and requiring a lengthy recovery time.
Prevention can involve an Osteopath to visit regularly and continually assess the horse for pain and mobility disturbances. A good Osteopathic practitioner will offer plenty of education and advice to allow owners to care for their horse’s backs and recognise signs early.
Bibliography:
Filippiadis, D.K., Mazioti, A., Argentos, S., Anselmetti, G., Papakonstantinou, O., Kelekis, N. and Kelekis, A. (2015). Baastrup’s disease (kissing spines syndrome): a pictorial review. Insights into Imaging, 6(1), pp.123–128. doi:https://doi.org/10.1007/s13244-014-0376-7.
Fiske-Jackson, A. (2018). Diagnosis and management of impinging spinous processes. UK-Vet Equine, 2(1), pp.15–21. doi: https://doi.org/10.12968/ukve.2018.2.1.15.
Hackney Horse Society. (2021). Breed Standard - Hackney Horse Society. [online] Available at: https://hackney-horse.org.uk/breed-standard/.
Hill, J. (2018). Kissing Spines in Horses: More Than Back Pain. [online] The Horse. AvailaJean-Marie Denoix (2019). Essentials of Clinical Anatomy of the Equine Locomotor System. CRC Press.
Jean-Marie Denoix (2019). Essentials of Clinical Anatomy of the Equine Locomotor System. CRC Press.
Rowe, P., Koller, A. and Sharma, S. (2023). Physiology, Bone Remodeling. [online] PubMed. Available at: https://www.ncbi.nlm.nih.gov/books/NBK499863/.
Young, A. (2019). Kissing Spines. [online] School of Veterinary Medicine. Available at: https://ceh.vetmed.ucdavis.edu/health-topics/kissing-spines.
Etalon (2023) Understanding Equine Kissing Spines: Symptoms, Causes, Diagnosis, Treatment & Prevention, https://etalondx.com/news-media/understanding-equine-kissing-spines-symptoms-causes-diagnosis-treatment-prevention/
.jpg)
.png)
.png)
