“Kissing spines” refers to a decreased space between the uppermost (dorsal) spinous processes of the vertebrae. The space between the spines can become so diminished that adjacent spinous processes can actually touch or even push past each other and overlap. This defect commonly results in pain at the site, and causes compensation in the rest of the musculoskeletal system. Horses with this condition therefore usually perform poorly, with or without signs of lameness. However, it must be noted that some horses with kissing spines are actually remarkably symptom free.
Kissing spines most commonly affect performance horses like Thoroughbreds and warmbloods. It is often difficult to find specific causes but predispositions are thought to arise due to conformation, poor saddle fit, incorrect riding style and even the discipline the horse is competing in. Kissing spine is generally not seen in foals suggesting human influence and age do play roles in its development.
The vertebrae most commonly affected are T15-18, probably due to the change in angulation of the spine at this point. However, kissing spine can also occur in the lumbar region and is not necessarily limited to just one or two vertebrae or even just one region.
In addition to lameness and poor performance other signs suggestive of kissing spine can be quite vague, but include behaviour changes, bucking under saddle, an unwillingness to jump, an unwillingness to go forwards, high head carriage and pain on palpation of the affected region. Diagnostic analgesia (injecting local anaesthetic) along with diagnostic imaging of the spine tend to be used to confirm the diagnosis in horses. Imaging may involve X-Rays, ultrasound or even nuclear imaging.
A wide range of treatment options are available including:
- Rest over a period of months is often needed.
- Local injection of anti-inflammatory drugs with a pain-relieving agent. This treatment will need repeating every few months.
- Extra-corporeal shock wave therapy.
- Bisphosphonate therapy.
- Surgical resection (removal) of the affected spinous processes.
- Interspinous ligament desmotomy, which involves making small cuts in the spinous ligament to create more space for the spinous processes.
Surgical treatments tend to be effective but have a long recovery process. If a horse fails to respond to the above treatments, it is likely that they should be retired.