A Controlled Study Evaluating a Novel Surgical Treatment for Kissing Spines in Standing Sedated Horses


Corresponding Author

Richard P. C. Coomer, MA, Vet MB Cert ES, Diplomate ECVS, Cotts Equine Hospital, Robeston Wathen, Narberth, Pembrokeshire, SA67 8EY, United Kingdom

E-mail: richcoomer@hotmail.com



To compare the results of a novel minimally invasive surgical technique with intralesional corticosteroid medication, as treatment for overriding dorsal spinous processes (ORDSP) in horses.

Study Design

Retrospective controlled clinical case series.


Horses (n = 68) with ORDSP.


ORDSP was diagnosed based on history, clinical, and radiographic examination. All narrowed spaces were treated. Horses undergoing medical treatment had methylprednisolone acetate injected directly in the affected space under radiographic control. Surgical cases had interspinous ligament desmotomy (ISLD) using Mayo scissors; supraspinous ligaments were left intact. All horses had the same controlled exercise plan and returned to work 3–6 weeks after treatment.


Methylprednisolone was administered in 1–7 spaces in 38 cases, compared with ISLD in 3–8 spaces in 37 cases. Thirty-four horses (89%) treated medically initially resolved signs of back compared with 35 horses (95%) treated surgically. From these, back pain recurred in 19 medical cases and in none of the surgical cases. Horses having ISLD were 24 times more likely to experience long-term resolution of signs of back pain (OR 24; 95%CI: 5–115; P = < .0001). Repeat radiographs in 19 surgical cases indicated that interspinous spaces widened significantly postoperatively (P = < .0001).


This surgical technique allowed horses with back pain and radiographic ORDSP to return to work without further clinical signs of back pain and to show radiographic evidence of improvement.