What is Kissing Spine in Horses?

Kissing Spine, scientifically known as overriding or impinging dorsal spinous processes, is the name for a condition in which the bones in the horses' spine have come close enough together to the point touching, or "kissing". In more serious cases, the vertebrae may overlap, and may manifest as more serious behavioral changes.

What Causes Kissing Spine?

Kissing spine can be caused by various factors, including:

1. Poor saddle fit
2. Moving incorrectly by not using the topline
3. Genetics
4. Conformation
5. Trauma to the back
6. Carrying too much weight

According to UC Davis, kissing spine typically occurs between the T13 to T18 vertebrae, which is where the saddle is placed, and, of course, where riders are seated. While this does point to saddle fit and weight distribution on the back being lead contenders for kissing spine, recent research has also pointed to kissing spine being a genetic phenomenon as well, meaning that riders and saddle fit may not only be the main factors in contributing to increased risk of kissing spine– in fact, it is estimated that a total between 30-40% of all horses have kissing spine, however some may show no signs of discomfort.

A study by Etalon shows potential in kissing spine being linked to "a region on Chromosome 25", and the company has even created a genetic test for kissing spine susceptibility. It is important to note here, that while the genetic testing could show promise to seeing whether or not a horse is susceptible to kissing spine, the test result is said to not be causative, meaning even if a horse is genetically susceptible, they may not contract kissing spine. Likewise, horses that are genetically sound may be diagnosed with kissing spine due to poor movement or trauma.

Signs of Kissing Spine

As previously mentioned, some horses may never show signs of kissing spine, however horses with more severe cases may display behaviors such as:

1. Bucking
2. Cross cantering
3. Discomfort in the canter
4. Worsening in performance level
5. Lameness
6. Being girthy or cinchy
7. Sensitivity to touch or grooming

While many of these are tell-tale signs of kissing spine, the only way to diagnose kissing spine would be by veterinary inspection, as some of these symptoms can be caused by other conditions such as stomach ulcers.

Diagnosing Kissing Spine

A diagnosis made by a veterinarian will consist of palpating the horse's back, followed up by any of the following:

1. X-rays
2. Bone scans
3. Ultrasound
4. Thermography (although less common)

Treatment and Prevention of Kissing Spine

Treatment may vary based on the severity of each individual affected by kissing spine. In general, horses with kissing spine may have to go through a physical rehabilitation through groundwork, where they use their core and build more topline. This is because, when horses are in a more correct frame and engaged in their core with a relaxed headset, the vertebrae in the spine begin to extend. This rehabilitation may be done through hand walking, lunging (often with a Pessoa system) or long lining, using an equine treadmill, or aqua therapy. This physical rehabilitation method of getting the horse to move correctly may also help to prevent kissing spine, so long as the issue is not genetic and the horse does not experience trauma to the spine. For more serious cases, injections may be considered, as well as surgery to shave down affected vertebrae.

For a more in depth explanation of kissing spine, this video by the University of Maryland shows visuals of kissing spine and explains how it affects the biomechanics of the horse.