History
A 2-year-old male entire labrador was referred for assessment of his hindlimbs. He presented with a stiff hindlimb gait, bunny hop at faster speeds and struggled to posture to toilet. He was restless at night, frequently changing positions. He had a tendency to keep the left hindlimb straight when lying down. He did not cry out in pain and could jump into the car without problems. He had longstanding problems with urination and needed to walk to initiate urination. He would often adopt an incorrect upright posture to defaecate. There were several episodes of urinary incontinence, usually when the bladder was overly full. He did not drip urine continually. The initial vet suspected hip dysplasia, but normal hip conformation was found on radiography. He was able to settle better with meloxicam.
Clinical signs
On presentation, the owner reported he was not using his hindlegs well. He intermittently lifted the left hindleg and occasionally the right. After squatting to urinate, he kicked out the left leg. He has occasionally whipped round to bite at his hip region on the left.
Gait examination was normal at walk but, when transitioning to trot, he had a couple of sudden hops on the left hind. Transition to canter also resulted in sudden hops on the left hind. He had a normal, symmetrical sit posture and down posture. Mild spasm was found when he was encouraged to stretch forwards in standing. Palpation was resented in the lower lumbar spine. Dorsoventral glides on the lower lumbar and lumbosacral junction were resented and avoidance action was taken with the dog dipping away or leaping to escape. There was normal, symmetrical muscling of the hindlimbs, no stifle pain or effusion, outward rotation and flexion of the hips was normal but extension of the hip and groin region on the right was resented and was not possible to assess on the left. There was no pain on palpation of the sciatic route through the hamstrings and no muscle pain found. There was no paresis or ataxia.
His clinical picture was one of intermittent pelvic limb pain, possibly nerve pain. In view of his young age and early onset of symptoms, I considered a congenital condition such as vertebral malformation, tethered cord or possibly discospondylitis. Gabapentin at 10mg/kg TID was prescribed and the dog showed improvement on this medication. The dog was referred for Neurological assessment and MRI investigation.
Test results
Hip radiographs were normal
Muscle enzyme activity, CK and AST normal
Genetic test for centronuclear myopathy and exercise-induced collapse normal
Electromyography unremarkable
Diagnostic imaging MRI
There were no structural abnormalities of the vertebral bodies, intervertebral discs, paraspinal muscles and ligaments. The conus medullaris terminates in the region of the L6/7 intervertebral disc and the thecal sac terminates at its attachment to the dorsal lamina of the sacrum in the S1 region. Flexed and extended views were then taken. This revealed a fixed termination of conus terminals at the level of the L6/7 IVDS, suggestive of Tethered Cord Syndrome
Treatment
An injection of 1mg/kg methylprednisolone was injected into the dorsal epidural space at L7/S1 under general anaesthesia. He then had 3 days restricted exercise before returning to normal exercise. He made a good recovery and clinical signs resolved to date (12 weeks) with no current medication.
Discussion
There is a lack of objective descriptions for the radiologic diagnosis of tethered cord syndrome in dogs. Often the diagnosis is made by excluding other orthopaedic issues and other causes of pain. MRI evaluation will determine whether the intra-thecal or extra-thecal filum terminale are short and putting tension on the nervous system, commonly causing pain and other neurologic deficits such as tail weakness and urinary incontinence.
The commonest age of onset is 11 months with a duration of clinical signs on average 13 months before diagnosis. Pain and dysthesia of the lumbosacral junction, tail or pelvic limbs is the commonest presenting sign. Medical management is usually reserved for patients with lesser clinical signs. Surgical untethering of the cord via a dorsal laminectomy often produces the best outcome.
Reference
Very special thanks to Colin Driver BSc BvetMed, MVetMed, PhD DipECVN FRCVS for his expertise with this case and allowing the sharing of his MRI images
Occult tethered cord syndrome: insights into clinical and MRI features, prognostic factors and treatment outcomes in 30 dogs with confirmed and presumptive diagnoses.
JE Romero et al 11/7/25 Front Vet Sci 12 2025