Hemilaminectomy and vertebral stabilisation for the treatment of thoracolumbar disc protrusion in 28 dogs.

OBJECTIVES

To evaluate the results of hemilaminectomy and vertebral stabilisation (+/- annulectomy) for the treatment of thoracolumbar disc protrusion.

METHODS

The medical records of dogs with thoracolumbar annular protrusions treated by hemilaminectomy and vertebral stabilisation were reviewed. Neurological function was assessed 24 hours following surgery. Long-term follow-up was by clinical examination or telephone questionnaire.

RESULTS

Twenty-eight dogs fulfilled the criteria. Age ranged from 4 to 12.5 years (median 8 years, mean 7.7 years), bodyweight from 5.1 to 51.5 kg (median 28 kg, mean 27.1 kg), and duration of neurological signs before presentation from 48 hours to 104 weeks (median 5 weeks, mean 9.3 weeks). At presentation 22 dogs were ambulatory and six were non-ambulatory. Myelography and/or magnetic resonance imaging (MRI) identified 31 thoracolumbar protrusions causing spinal cord compression. Unilateral hemilaminectomy was performed in 27 dogs and bilateral hemilaminectomy in one dog. Partial annulectomy was performed in 24 of 31 protrusions. Stabilisation was performed using vertebral body bone plates in 26 dogs and vertebral body screws and bone cement in two dogs. Internal vertebral venous plexus haemorrhage was recorded in nine dogs. A screw was inadvertently placed into an intervertebral disc in two dogs. Neurological examination 24 hours postoperatively revealed deterioration in pelvic limb motor function in 17 dogs. One dog was euthanatised at the owner's request 6 days after surgery. Long-term evaluation of 24 cases was performed 3 to 52 months following surgery (median 21 months, mean 23.9 months). Six dogs had improved from their preoperative status and one had deteriorated as assessed by the authors. Fifteen dogs had improved from their preoperative status and two were unchanged as assessed by owners.

CLINICAL SIGNIFICANCE

Hemilaminectomy and vertebral stabilisation are an effective treatment for chronic spinal cord compression due to thoracolumbar annular protrusion in dogs. A temporary deterioration in neurological function is not uncommon following surgery. Internal vertebral plexus haemorrhage and inappropriate vertebral body screw placement are potential complications.