Case Report: Segmental spinal cord hypoplasia in a Labrador Retriever puppy

This case report describes the clinical, diagnostic imaging, and histopathologic findings of spinal cord hypoplasia in a 13-week-old, intact male Labrador Retriever. The dog was first presented at 6 weeks of age with chronic and progressive gait abnormalities and fecal and urinary incontinence. On clinical examination, the puppy was bright, alert, and responsive but smaller than its siblings and showed poor muscle mass. No abnormalities were found in the general examination. Neurologic examination revealed mild kyphosis of the lumbar spine, ambulatory spastic paraparesis, proprioceptive pelvic limb ataxia, and a "bunny-hopping" gait. Orthopedic examination did not show any additional abnormalities. Bloodwork for infectious and metabolic etiologies was within normal limits. Magnetic resonance imaging (MRI) of the vertebral column revealed thinning of the thoracolumbar spinal cord with a compensatory increase in subarachnoid space volume, suggestive of spinal cord hypoplasia. In consultation with the owner, euthanasia was elected, given the poor expected quality of life. Postmortem examination showed moderate lumbar kyphosis and mild thoracolumbar scoliosis. Macroscopically, the thoracolumbar spinal cord was multifocally thinned with a markedly irregular dorsolateral surface. Histological examination demonstrated markedly thinned segments with bilateral and symmetric dorsolateral white and grey matter hypoplasia, with the remnant white matter displaying an abnormal conformation with prominent edematous changes. Segmental spinal cord hypoplasia is described as a rare disorder in humans and a few animal species. To the authors' knowledge, this is the first reported case of segmental spinal cord hypoplasia in a dog.