Kissing spines – what is it and how can you help your horse?

Kissing spines can be a debilitating condition, but there are things that can be done to help your horse return to optimum health. Here, we take a look at the symptoms of kissing spines, what causes the condition and some treatment options.

What are kissing spines in horses?

Also known as overlapping or impinging dorsal spinous processes, kissing spines involve the bones along the horse’s spine, from the withers (T1) to the point of the hip (L6).

The T13 to T18 spinous processes are most commonly affected, as this is the area where the saddle and rider are carried. In a ‘normal’ horse, the spinous processes are spaced evenly with a gap between each one, and this allows the horse to easily flex and extend their back. When a horse is suffering from kissing spines, these bones have a smaller gap between them, or in some cases are so close that they are actually touching, which can cause a lot of pain, especially when a horse is ridden.

What causes kissing spines?

There are a number of factors that can cause a horse to develop kissing spines. These include:

• Predisposed breeds: research indicates that warmbloods, thoroughbreds and quarter horses are more likely to develop kissing spines due to genetics and the fact they are commonly ridden at a younger age before reaching full skeletal maturity.
• Conformation: horses with a shorter-than-average back are more likely to develop kissing spines because they have the same number of vertebrae in a smaller area, resulting in less space between the vertebrae.
• Genetics: research indicates that specific chromosomes could increase the risk of kissing spines, meaning affected horses can pass it down to their offspring.
• Incorrect training: horses that are ridden with a high head and hollow back or trained under saddle too young are more likely to develop kissing spines. A weak topline and back mean a horse can’t carry a rider properly and the back is not able to lift and spread the spinous processes apart.
• Hoof angles: horses with low or collapsed heels can cause uneven pressure on the hoof wall and sole, which causes a horse to stiffen their back in a hollow posture, resulting in kissing spines.
• Accompanying conditions: horses with hock and sacroiliac arthritis will often move their back incorrectly, meaning they are more likely to develop kissing spines.

Symptoms of kissing spines

Some horses diagnosed with kissing spines via X-ray live with the condition without showing signs of discomfort and have a successful ridden life without requiring any veterinary intervention.

In horses that do have pain from kissing spines, the clinical signs are as follows:

• Discomfort when pressure is applied along the spine and adjacent muscles
• Pain, tail swishing and pinning their ears back when the saddle is put on
• Changes in attitude to ridden work, such as not wanting to go forward, refusing when jumping, bucking or a reduction in performance
• Lack of musculature (topline) along the back and hindquarters. A poor topline will result in a dipped back, leading to further narrowing of the spaces between the dorsal spinous processes. Subtle hindlimb lameness or sacroiliac pain, which can develop as compensatory secondary issues
• Many horses will dislike being tacked up, as they associate the saddle with pain. They could also be ‘cold-backed’ when the girth is tightened and the rider first gets on
• Some horses struggle to lift their back to work in an outline or arc when jumping

Diagnosis options

The most common way to diagnose kissing spines is by X-raying the back, focusing on the dorsal spinous processes. This will show if there are any areas of bone reaction (which show up as whiter areas of bone) or bone that may be touching and causing pain.

If the vet is unsure whether the horse’s back pain is definitely caused by kissing spines, they can nerve-block the back using local anaesthetic to assess for the presence of pain, or refer the horse for a bone scan to identify any areas of reactive bone over the back.

Treatment for kissing spines

Treatment for kissing spines is split into two categories; medical management and surgery.

• Medical treatment aims to make the horse comfortable using steroid injections into the gaps between the spinous processes and adjacent musculature, so they can then be worked in a way to build up the muscles over the back and hindquarters, lifting the back and reducing the ‘crowding’ of vertebrae. A specific exercise plan is followed using in-hand, lunging and pole work, followed by ridden work that focuses on rounding and raising the back to ‘open’ the spinous processes.
  
• Surgical intervention is advised if there isn’t any improvement with medical management, or if there are severe changes on the X-rays. Surgery involves breaking down or decompressing the ligament which runs between the areas of compression. The idea is that if the ligament is no longer being pinched, then the pain will stop. In cases where the vertebrae are overlapping or touching, then removal of either the front of the affected vertebrae or a significant portion of it may be recommended – this is very invasive and requires a longer recovery time.

Prognosis

Most horses diagnosed with kissing spines are able to return to ridden work after appropriate veterinary treatment and a recommended rehab programme is completed. In some cases, they may be unable to return to the same level of work as before but are comfortable working at a lower level.

Paddock retirement is an option for most horses if veterinary treatment and rehabilitation isn’t feasible. Very few horses with kissing spines require euthanasia, unless they have other underlying issues that cause ongoing pain.