Myelopathy secondary to generalized thoracic caudal articular process aplasia in a non-brachycephalic breed dog: a case report

A 5-month-old mixed-breed dog was presented with progressive ambulatory paraparesis. Neurological examination was consistent with thoracolumbar myelopathy. Magnetic resonance imaging (MRI) revealed a spinal (sub)arachnoid diverticulum (SAD) at T8–T9 with spinal cord compression associated with central canal dilation and intramedullary edema. Computed tomography (CT) showed generalized caudal articular process dysplasia (CAPD) from T2 to T9 vertebras. Considering diagnostic imaging results, symptoms were strongly suspected to be due to spinal cord compression associated with CAPD-induced SAD. Surgery was performed and cystic structure was detached. One month after the surgery, no progression of clinical symptoms was observed. To the best of our knowledge, this is the first reported case of SAD causing thoracolumbar myelopathy in a non-brachycephalic dog with generalized CAPD. These findings highlight the potential role of CAPD as a contributing factor to SAD formation. A combination of CT and MRI is recommended for thorough evaluation of vertebral structures and alignment in similar cases.