It’s the diagnosis that often lingers in the back of a horse owner’s mind when their horse starts showing signs of back pain, girthiness, or poor performance. But what exactly is “Kissing Spines,” what triggers its development, and, most importantly, what can we so to treat and manage this condition?
In this blog, we will attempt to demystify the condition, from the anatomy of the vertebrae to the latest in treatment and care.
What exactly is “Kissing Spines”?
The technical term for this condition is Overriding Dorsal Spinous Processes (ORDSP). Each vertebra in the horse’s spinal column has a bony projection called the spinous process. These project upwards and can be palpated along the spine or backbone. Normally there is a very small gap between these spinous processes, but in ORSDSP, the spinous processes are too close and touch or even overlap. This is most likely between the thoracic vertebrae, where the saddle fits.
What are the clinical signs associated with this and what causes it?
Many horses with mild signs will not show any symptoms at all. Others may be misunderstood as being “naughty” or difficult. The most commonly reported signs include resistance to the saddle or being ridden, with particular difficulty in going forward or with transitions. These horses tend to shoot forward and work with a hollow outline. Horses may also show greater reactiveness to being brushed or saddled, all consistent with back pain.
One of the main contributing factors in the development of this syndrome is genetics, Thoroughbreds and Warmbloods are overrepresented, although of course these are also breeds that are involved in high level ridden work. In addition to genetics and confirmation, other causes such as ridden exercise, particularly being ridden in a hollow outline, are often implicated. Younger horses, started into ridden work at an early age may work in a very hollow outline, which could contribute to the development of the disease.
How do we diagnose this?
Diagnosis can be challenging as the signs listed above could occur with other conditions such as back pain, lameness, gastric ulcers or training issues. The first step is for us to listen to a detailed history of the problem to try to rule out other causes. We will then normally examine the horse at rest, when trotted up, and lunged, as well as ridden under saddle if it is safe to do so. Many causes of “back pain” are in reality hindlimb lameness, so we will try and rule this out first.
Once we have established that back pain is the likely cause of the problems, we then usually move on to further diagnostics. Radiography is often used to visualise the spinous processes and the articular facets of the spine. With kissing spines, we can see overriding or touching of the spinous processes. However, the apparent presence of overlapping spines on a radiograph alone is not always sufficient to diagnose the condition, and so in some cases, nerve blocks, or injections of local anaesthetic may be used. Other imaging modalities that we may recommend include ultrasound or nuclear scintigraphy, also known as a bone scan. These are used to give a clearer picture of active inflammation or secondary issues.
How can we treat and manage this condition?
In most cases, conservative management is the first line of action. In this, the goal is to reduce inflammation and strengthen the core muscles supporting the spine. Usually, we would recommend shockwave, mesotherapy, or steroid injections. Mesotherapy is the injection of anti-inflammatory drugs and anaesthetics into the deeper layers of the skin along the back. These treatments aim to reduce muscle spasms and pain to allow the horse to move more comfortably. Once the horse is more comfortable, physiotherapy and rehabilitation to encourage the horse to work in an outline, can begin. It is hoped that by strengthening the muscles and ligaments of the back, the spine can move more freely and with less impingement.
If there is not enough improvement with conservative treatment and management, we would suggest considering surgical options. There are two main choices, Interspinous Ligament Desmotomy, where the ligament between the spinous processes is cut, to reduce the tension. In more extreme cases, an ostectomy, the surgical removal of parts of the spinous process is removed, may be warranted. Both these procedures tend to be carried out with the horse standing, under heavy sedation and pain relief.
The prognosis is generally quite good for these cases, but it should be noted that any cases will need a great deal of commitment with physiotherapy and rehabilitation plans. We are always very happy to work with physiotherapists and trainers to help you to develop the correct management plan for you and your horse.
If you are concerned that your horse may have a back issue or would like some advice on any aspect of veterinary care, please do not hesitate to contact the office where our vets would be delighted to talk to you.
