An 8 month old, male intact, German Shepherd presented to Cornell University Hospital for Animals (CUHA) Emergency service for a 2 week history of unlocalized pain. Initially, the dog presented to his referring veterinarian for intermittently vocalizing, sometimes in response to touch. Abdominal radio graphs were performed by the referring veterinarian due to concerns of a foreign body, but did not show any abnormalities. The dog was discharged with carprofen and gabapentin. There was no improvement in his pain so the dog re-presented to the referring veterinarian where he tested positive for Lyme disease. He was discharged on a course of doxycycline but continued to be intermittently painful and then became ataxic and disoriented. He was then referred to Cornell University Hospital for Animals for further evaluation. On presentation to the emergency service the dog was quiet, alert and responsive with a kyphotic posture. Decreased proprioception was detected in both pelvic limbs with intact spinal reflexes. Mid to caudal thoracolumbar pain was present. The most significant problems identified were para-ataxia, decreased pelvic limb proprioception and mid to caudal thoracolumbar pain. The dog's neurological signs were localized to a T3-L3 myelopathy with the most likely differentials based on his age and clinical signs being fungal or bacterial discospondylitis or myelitis, nephroblastoma or other neoplasia. A thoracolumbar magnetic resonance imaging (MRI) was performed and showed an I lx5x7 cm heterogenous paraspinal mass centered on T7 and invading vertebral bodies ofT4- T7. An ultrasound guided fine needle aspirate was performed and cytology showed numerous dense globular to tubular aggregates of tumor cells. It was interpreted as most likely a primitive tumor with the top differential being a nephroblastoma. Cerebrospinal fluid (CSF) findings were nonspecific but indicated underlying central nervous system (CNS) pathology. Based on the top differential of neoplasia and the poor prognosis associated with a large paraspinal mass, euthanasia was elected and a necropsy was performed. Necropsy confirmed a paravertebral neoplasm centering on T6-7. The histological diagnosis was a presumptive primitive neuroectodermal tumor or a Ewing's sarcoma. After immunohistochemical staining was performed, the most likely diagnosis was a primitive peripheral neuroectodermal tumor.

This is a discussion of the neurological examination and MRI findings, the necropsy findings, the immunohistochemical stains and the prognosis of the tumor.