Spinal Epidural Lipomatosis Secondary to Hypothyroidism in a Siberian Husky Dog

A 10-year-old neutered male Siberian Husky presented with paraparesis and severe lethargy. On physical examination, the patient was unable to weight-bear and walk and exhibited significant muscle mass loss in both hindlimbs and generalized truncal alopecia with a dull coat of hair. On neurological examination, cranial lumbar vertebral pain, hind limb cross-extensor reflex, delayed hindlimb postural reaction, upper motor neuron bladder dysfunction, and total absence of cutaneous trunci reflex were identified. Computed tomography revealed diffuse idiopathic skeletal hyperostosis and spondylosis deformans of the cervical and thoracolumbar vertebrae. In addition, a generalized decrease in bone mineral density of the vertebrae was identified. Magnetic resonance imaging showed hyperplasia of the epidural fat compressing the spinal cord in the thoracolumbar region and concurrent mild multiple intervertebral disc herniations. No specific findings were observed in cerebrospinal fluid analysis. Blood analysis of thyroid function revealed decreased total T4 and free T4 levels, and increased TSH levels. The patient was tentatively diagnosed with spinal epidural lipomatosis (SEL) secondary to hypothyroidism. The patient was treated with levothyroxine, firocoxib, and gabapentin. Clinical signs gradually improved, and the patient showed normal ambulation 40 days after treatment initiation. SEL is extremely rare in dogs. To the best of our knowledge, this is the first case report of SEL secondary to hypothyroidism that was treated conservatively. Secondary SEL can be sufficiently managed by treating the underlying cause, if possible.