Abstract
A 2-year-old female Clydesdale horse was anesthetized in dorsal recumbency for an elective surgical procedure to treat osteochondritis dissecans involving the intermediate ridge of the right tibia. Following surgery, the horse lost motor and sensory function in the hind limbs and was unable to stand. The status deteriorated and the horse was euthanized 20 h post-surgery. Histopathologic examination revealed mild to moderate acute myelopathy of the spinal cord between T14 and S3. The lesions were bilateral, with one side being slightly more affected, and more severe in the distal lumbar and sacral spinal cord segments. Immunohistochemistry for beta-amyloid precursor protein (β-APP) was compared to other fast axonal transport proteins such as neurofilament heavy protein, synaptophysin, and ubiquitin. In the presented case, the β-APP immunohistochemistry revealed positively-labeled, multiple, segmentally-swollen axons (axonal bulbs) and rarely neurons. The positively-stained areas overlapped with the lesions seen on HE stained slides including areas in which changes were poorly discernible by routine histologic exam. Amongst the fast axonal transport proteins detected via immunohistochemistry, β-APP was considered adequate to use as a potential sensitive biomarker for axonal injury in this case of post-anesthetic myelopathy. β-APP immunohistochemistry may be a useful tool to study and diagnose axonal injuries of the central and peripheral nervous system in veterinary medicine.