Kissing spines is the name of an equine disorder in which the spaces between dorsal spinous processes are dramatically reduced to the point where these touch. A diagnosis doesn’t necessarily mean the end of your horse’s career, however. Below, we discuss how back problems arise and how they can be treated, with exercise and supportive measures playing an important role.
First, let’s take a look at a horse’s back. The back of a horse can be compared to a bridge construction. Forehand and hindquarters are the piers, whilst the 18 thoracic, 7 cervical and 6 lumbar vertebrae form the elastic bridge we know as the spine. The individual vertebrae are connected by ligaments and surrounded by muscle. Each vertebra has a bony upward protrusion known as the spinous process. In a healthy horse, the distances between the spinous processes are evenly spaced, allowing the horse to bend and arch its back easily through the use of its back muscles.
Kissing spines (or kissing spine) is the common term for when dorsal spinous processes are so close together that they touch and may even overlap. The lack of space reduces movement in the spine and causes pain during exercise, and the rubbing of the spinous processes leads to inflammations and subsequently to bone distension and growths that can cause the horse great pain. The disease can affect any horse, but thoroughbreds and warmbloods seem to be affected more often than other breeds. Diagnoses are made most frequently in horses between the ages of five and ten. It occurs most typically in the last thoracic vertebra, over which the saddle rests and the rider sits.
The back pain can manifest itself in a wide variety of symptoms:
- Pain sensitivity while being groomed or when the back is touched
- Displeasure during saddling and/or mounting
- Saddle or girth aversion
- Unwillingness and reluctance to go forward with impulsion when ridden
- Behaviour under saddle ranging from nervous to hysterical
- Drop in performance, long warm-up phases
- Stiff back
- Crooked or clamped tail, tail swishing
- Chewing activity during riding
- Stiff, short stride, faults in rhythm such as abnormal gaits
- Resistance in rein backs, tempo changes, or lateral movements
- Jumping at the wrong canter, cross cantering, “bunny hop” canter
- Reduced carrying capacity of the hindquarters, pulling the reins out of the rider's hands, resistance to collection
- Rearing, bucking, kicking, or bolting during certain moves, making grunting or groaning noises under the saddle
- Jumping “without the back”, refusal at jumps
- Worsening after stall rest.
A stiff, painful back musculature is considered a clear sign of kissing spines. However, a word of caution: if the disease has been present for a long time, it can also cause the sensory system of the back muscles to “switch off”, i.e., the horse no longer feels back pain from pressure while other symptoms remain. Some of these signs might lead one to think that the horse is simply being naughty or resistant, which can undoubtedly happen. However, before a previously cooperative horse is “corrected”, the cause for the behavioural changes should be explored. Horses have no language to express pain other than through their behaviour.
When symptoms are acute, the trigger for the pain is often found quickly. Symptoms can appear within 24 hours after an incident like getting trapped or falling, causing twisting to the vertebrae. Mostly, however, it is a gradual process that occurs over months or even years. Possible causes include longer relieving posture through lameness or injury, particularly if the horse has been brought back in work too soon. Other causes may include:
- Faulty schooling/training
- Overload (sore muscles)
- Poor saddle fit
- Wrong shoes or hoofwork
- Problems in the teeth or jaw
- Confined stabling with little space to move
- Muscle metabolism diseases like PSSM, EMS, and KPU
- Digestion problems, stomach aches
Each of these factors can cause the back muscles to no longer work properly and result in increasing tension.
Can riding “wrong” cause kissing spines?
The back of a horse is not naturally designed to carry a rider. The rider sits just above the spine on the long, floating bridge between the forehand and the hindquarters. However, to call kissing spines a vocational illness of riding horses would not be completely accurate. The oldest “findings” of changes to the spinous processes in a horse is from 40,000 years ago, long before humans began to ride horses. This narrowing of the spinous processes is usually a congenital disorder. However, it can become a problem if muscle development is neglected in training and the young horse is already pressed into the desired shape while being broken. Add to this a rider who is overweight, has a rough riding style, a crooked seat, sits behind the movement or has a hard hand, and back problems are inevitable.
Faulty schooling and training
Moving on the forehand, hollow back, auxiliary reins that pull the horse’s head down, “Rollkur” and other methods are intended to accelerate the horse’s schooling – any of these can lay the foundation for back problems like kissing spines. Schooling and training should always be carried out with the goal of building muscle in the horse, to allow it to engage the hindquarters and flex the back in order to bear the rider’s weight.
How do kissing spines develop?
Muscle tension in the back blocks the mobility of the vertebral joints, and thus a vicious circle begins: this blockage causes the back muscles to degenerate, the distances between the vertebrae to decrease, and inflammatory processes to develop. In reaction to the inflammation, bone growths develop on the spinous processes until, as the course progresses, the dorsal spinous processes touch and fuse together with a neighbouring vertebral process at the ends, but possibly also in middle or lower areas.
Diagnosing kissing spines is difficult, and often imprecise. Vets must therefore approach the findings in several steps. The first step focuses on the assessment of the back musculature of the standing horse. Limited mobility caused by the pain of kissing spines often leads to localised or generalised atrophy of the back muscles, lopsided muscularisation of the back, increased muscle tension, and pressure pain. Getting the horse to lift his back by applying pressure to the Linea alba can narrow down the tension to a specific area.
Pain symptoms are usually more obvious when the horse is observed in motion. When being lunged without a girth, the horse often has balance problems and leans into the curve instead of bending. Lungeing with a girth often leads to symptoms worsening. When possible, the horse should be ridden for the vet to rule out other back problems.
An X-ray will provide more precise information on possible changes to the spine. This will show not only the dorsal spinous processes but the vertebral bodies and the joints in between as well, since the causes for kissing spines are often found deeper in. Changes are classified in three grades depending on the severity, which an X-ray examination will determine.
- Grade I: Decreased space between two or more dorsal spinous processes with low-grade hardening (sclerotisation) of the cortical bone consisting of fibrous tissue
- Grade II: Two or more touching dorsal spinous processes with moderate sclerotisation of the cortical edges
- Grade III: Two or more touching and overlapping dorsal spinous processes with sclerotisation of the cortical edges and/or first sign of bone resorption
Despite all the care taken with X-rays, misdiagnoses do occur. The angle from which the radiograph is taken can give false distances between the bones. In young horses, the position of the dorsal spinous processes changes until the age of 7 or 8; in older horses, remodelling processes of the spine can be related to age and wear, without the horse experiencing any pain. A suspected case of kissing spines is not confirmed until radiographically determined changes are matched with palpable or visible symptoms.
Other diagnostic options
Diagnostic anaesthesia involves numbing the painful area on the horse's back with a local anaesthetic. The horse should then be ridden once more. The rider should feel any improvement, which is not always visible.
An ultrasound can reveal pathological changes to ligaments and tendons and the periosteum of the dorsal spinous processes in the treated area. Inflammations of the vertebral bodies can be detected through scintigraphy. This is a complex procedure in which the horse’s vein is injected with a radioactive drug which, in combination with a second drug, can accumulate in inflamed bone areas. The radiation is measured with a special camera. This examination is helpful because horses with back problems often have a larger number of dorsal spinous processes located close to one another and not all of them cause complaints. For a scintigraphic examination, the horse must be brought to a clinic. After two days, the drug breaks down so that the horse is no longer exposed to radioactivity.
There is no uniform treatment for kissing spines. Treatment is primarily aimed at relieving the pain and inflammation. Anti-inflammatory medications or local injections are often employed. Pain therapy should improve the horse’s mobility to the extent that it can begin rehabilitation. Surgery, involving either the cutting of the ligaments between the dorsal spinous processes or the grinding or sawing out of the spinous process, is possible but very rarely performed.
Manual therapy, chiropractic therapy and acupuncture often bring success, with treatment focusing on the dissolution of blockages and relaxation of the back muscles. Heat treatments in a horse solarium have proven successful, as has rugging the horse with a ceramic fibre rug, which improves blood circulation in the muscles.
African devil’s claw is a known natural anti-inflammatory and analgesic plant. It can also be used for sustained periods of time because, unlike chemical painkillers, it won’t damage the horse's stomach lining. Hemp nettle contains harpagoside, the same substance found in devil’s claw, and supports its effect. Willow is known as Nature’s aspirin and relieves chronic musculoskeletal pains.
What about stabling?
Horses with back problems should be given lots of room to move about. Ideal stabling would be with a compatible herd in an open stall and/or turned out. Slow, forward movements with the head in a low position stretches the muscles, whilst rolling on the ground and bucking can loosen up tight muscles. If possible, hay should be laid on the ground. Hay nets and mangers don’t allow for natural feeding postures. Caution with mixed groups: Some “studdy” geldings will mount mares in heat, which, if they have back problems, can cause further damage!
Can a horse with kissing spines be ridden again?
One prime example of how horses with massive changes to their spinous processes can make it in top sport is the thoroughbred Bantry Bay. The eventing champion was prepared by his rider for the Olympic Games with patience and special training. Even if your equestrian ambitions are not quite that high, if your horse is rideable again after pain treatment, with targeted rehabilitation training it can regain full fitness. Avoid lunge work, replacing it with in-hand gymnastics. It’s essential to build a back musculature that is stable and can bear loads. When riding in correct extension posture with an engaged hindquarters, the back begins to swing, the ligaments and muscles between the vertebrae are stretched and the spinous processes are pulled away from each other.
Caution: Forward-and-down riding is very strenuous for horses, so don’t overdo it!
Info: In the past, horses were harnessed to carriages if they had back problems when ridden. Light pulling works the back muscles while the back stays free. Not every horse will be enthusiastic about doing this, but it’s worth trying.
Starting again: natural substances promote muscle development!
You can support the development of a stable back musculature in your horse by feeding it herbs. Herbal supplements contain natural substances that keep muscle metabolism active and supply the muscles with amino acids, vitamins, minerals, and antioxidants. Sea-buckthorn and rose hips are real vitamin bombs. Vitamins C and B3 as well as provitamin A are important for muscle development. Grape seeds are called “super-antioxidants” because they contain OPC. They can boost the effects of vitamin A, C, and E. Hawthorn has vasodilatory properties and strengthens the cardiovascular system. Ginkgo promotes blood flow and improves the flow of oxygen and nutrients to the muscle cells. Spirulina contains valuable proteins and amino acids that the organism needs to build muscle. Linseed has an amazing amount of omega-3 fatty acids and provides muscles with energy.
Can kissing spines be prevented?
A recently published study in the USA showed that the risk of developing kissing spines is hereditary. To a certain extent, however, the painful stages of this disease are preventable. Tack should be regularly checked, for example. A poorly fitting saddle can have devastating impacts for the horse’s back. The saddle should be checked and, if necessary, adjusted at least once a year and after longer breaks in training. Auxiliary reins should only be used by pros, if at all, and never continuously.
Bad habits can creep into even the best riders’ techniques. You horse will benefit from a regular review of your riding skills by a professional trainer.
Your horse should also be seen by an equine dentist once a year. Dental or jaw issues can lead to severe tension. Have a competent veterinary surgeon check the horse’s teeth once a year for any problems. Blockages and tension should be given prompt treatment. Physical therapy will be good for both horse and rider.
A kissing spines diagnosis – (no) reason for panic?
It is not uncommon for radiographic examinations done for other reasons to reveal changes and growths of the dorsal spinous processes which do not affect the horse in the least. A study conducted on 295 clinically healthy, fit horses at the University of Munich found that X-rays showed changes to the spinous process in the saddle area in 91.5 percent. Even young horses that have never been ridden showed shortened spacing and overlapping of the spinous processes.
However, experts advise against letting an X-ray be the deciding factor when buying a horse. The risk of any abnormalities leading to complaints is thought to be lower than the exposure to radiation from X-rays. With riding skill, sensitivity, and timely supportive measures to enhance the horse’s well-being, even less-than-perfect horses can become wonderful partners.
- Christina Fritz, Souel Maleh: Zivilisationskrankheiten des Pferdes. Ganzheitliche Behandlung chronischer Krankheiten, Thieme, Stuttgart/New York, 2. Aufl. 2016
- Matilda Holmer, Bettina Wollanke und Guido Stadtbäumer (Tierklinik Telgte und Pferdeklinik der Universität München): Röntgenveränderungen an den Dornfortsätzen von 295 klinisch rückengesunden Warmblutpferden, in: Pferdeheilkunde 23 (2007) 5 (September/Oktober) 507-511
- https://Kissing Spine¬_VÖPNewsletter (=pferdeklinik-pegasus.at/wp-content/uploads/2021/12/NL_Kissingspine.pdf)