Marked Cauda Equina Compression Secondary to Intervertebral Disc Protrusion Resulting in Severe Chronic Neuritis and Neural Fibrosis in a Dog.

A 7-year-old male intact German shorthaired pointer was referred to a board-certified veterinary neurologist for further evaluation of a chronic (> 6 months) history of gradually progressive paraparesis, limp tail, and spinal pain despite medical management of these clinical signs and presumptive neurologic disease with the family veterinarian. Radiographs revealed evidence of intervertebral disc space collapse, endplate sclerosis, and bridging spondylosis at L7-S1, and the patient was presumptively diagnosed with degenerative lumbosacral stenosis (DLSS). Initial medical management included oral analgesics, oral anti-inflammatories, lifestyle changes, and epidural steroid injections. Ultimately, progression of the patient's clinical signs resulted in referral to a board-certified veterinary neurologist. Magnetic resonance imaging revealed marked bilateral L7 nerve root enlargement with L7-S1 foraminal widening and concurrent L7-S1 intervertebral disc extrusion, causing moderate to severe left-sided compression of the cauda equina. Given the marked changes of nerve roots on imaging and foraminal widening, consideration was given to a neoplastic process versus inflammatory neuritis. A lumbosacral dorsal laminectomy, partial discectomy, and left L7 nerve biopsy were performed. Histopathology of the L7 nerve root revealed chronic neural fibrosis with atrophy and mild neuritis, consistent with the chronic, progressive nature of the patient's clinical signs and severe compression of the cauda equina. These dramatic and irreversible changes may have been avoidable or at least minimized with earlier diagnosis and aggressive surgical intervention, highlighting the importance of developing standardized, evidence-based recommendations for management of dogs with DLSS similar to the framework that exists in human intervention for treatment of cauda equina syndrome (CES).