A 6-year-old Thoroughbred Irish Sport Horse gelding presented to the Cornell Equine Orthopedic Service for a 3 month history of back soreness and objection to exercise. Prior to presentation at Cornell, the gelding began showing signs of poor performance and a reluctance to train, including resistance to saddling and hypersensitivity to palpation of the back and hind quarters. On presentation, the patient demonstrated a strong objection to palpation of the neck, back and hindquarters, and had firm epaxial muscles that spasmed in response to deep palpation. Lameness examination revealed a grade 2/5 (AAEP lameness score) left hind limb lameness and bilateral mild pain response of the sacroiliac joints. Nuclear scintigraphy exhibited two focal regions of increased radiopharmaceutical uptake in the caudal thoracic and mid to caudal lumbar region. Subsequent thoracolumbar radiographs revealed evidence of multifocal mild to moderate overriding dorsal spinous processes with mild associated degenerative changes in the caudal thoracic and lumbar back. These diagnostic findings suggest the history and presenting clinical signs to be attributed to overriding dorsal spinous processes. The treatment plan included injecting five sites in this region with corticosteroids, a two week course of muscle relaxant medication, a brief period of rest and gradual return to work.
The following report will present a case of a horse diagnosed with overriding dorsal spinous processes (ODSP’s), as well as discuss common presenting signs, diagnostic modalities and both medical and surgical treatment options for overriding dorsal spinous processes in the horse.