Kissing spine is a skeletal abnormality in horses in which bony projections on the vertebrae of the spine touch or “kiss”. These projections are called dorsal spinous processes.

This condition is caused by multiple factors including conformation issues, genetic predispositions, poor posture, improper conditioning, and training under saddle at a very young age.

Horses with kissing spine do not always develop symptoms, but many horses with this condition experience back pain. Afflicted horses may exhibit extreme back tightness, bucking, pain on palpation and an inability to stretch and raise the back while under saddle.

Most horse owners dread having their horse diagnosed with kissing spine. For a long time, it was thought that horses with symptomatic kissing spine could no longer be ridden and had to be retired.

However, surgical advances and modern rehabilitation techniques give new hope to owners of horses with kissing spine. There are many therapies available to keep your horse comfortable and to re-establish mobility.

Have your veterinarian examine your horse if you think they are experiencing back pain. If left untreated, horses with kissing spine can act out under saddle, putting themselves and their riders at risk.

Kissing Spine: An Emerging Concern

Kissing spine is sometimes referred to as dorsal spinous process impingement syndrome.

Kissing spine commonly affects multiple vertebrae of the thoracic spine, in particular T14- T18. This is the area around the anticlinical vertebrae or the area of the spine where the dorsal spinal process change orientation. This is also the area under the saddle and the rider. However, it can occur along the entire length of a horse’s back. [15]

This condition is diagnosed by a veterinarian upon radiographic detection of overriding dorsal spinous processes (ORDSP). Kissing spine diagnosis has increased significantly in recent years due to the increased use of digital radiographs (x-rays). [2]

Your veterinarian will perform x-rays along the spine to determine whether the vertebrae in the spine are too close or touching. When examining an x-ray of the back, veterinarians look for reductions in the space between dorsal spinous processes and changes to the boney areas.

Dorsal spinous process impingement syndrome in horses | Mad Barn Canada

Ultrasound imaging can also be used to assist with diagnosis. It can be combined with the information in the x-rays to give information of changes the dorsal spinous process surface, supraspinous ligament damage, multifidus muscle changes and facet joint involvement.

Your veterinarian may also suggest a bone scan (Nuclear Scintigraphy), which involves injecting your horse with a radioisotope and using a bone scan camera. The camera is positioned over your horse’s back to detect hot spots – areas where radiation is absorbed into the bone. These hot spots indicate areas of inflammation and likely pain. [1]

Bone scans are considered more accurate in differentiating clinical versus non-clinical cases of kissing spines. These scans are usually only conducted at referral practices.

Some veterinarians will use local anesthesia (freezing) to test if blocking the pain helps alleviate symptoms of kissing spines.

Back Pain in Horses

Kissing spine does not always cause pain in horses. In fact, some cases of kissing spine are found accidentally while investigating other issues in asymptomatic horses. In one study 39% of horses that were radiographed despite lack of back pain still had radiographic changes suggestive of kissing spines. [16]

However, in the same study, 68% of horses that did present for back pain were diagnosed with kissing spine. This suggests that this condition is a major contributor to equine back name.

When kissing spine does cause pain it can be quite severe. Horses with this condition can experience pain for the following reasons:

  • The bony dorsal spinous processes grinding against each other
  • Injury or inflammation of the ligaments between the processes
  • Reduced of range of motion in affected vertebral segments, resulting in muscle tightness
  • Impingement of the nerves exiting the spinal cord through the foramen of the affected vertebral segments