The cutaneous trunci reflex for localising and grading thoracolumbar spinal cord injuries in dogs

Objectives: To evaluate the accuracy of the cutaneous trunci reflex to localise thoracolumbar spinal cord injuries and to assess the correlation between focal loss (cut-off) of the reflex and clinical severity of thoracolumbar spinal cord injury. Methods: Prospective study of 41 dogs with thoracolumbar spinal cord injuries investigated by magnetic resonance imaging. Linear regression analysis was performed to determine the relationship between the vertebral level of the cutaneous trunci reflex cut-off and the maximal and cranial lesion extent. The association between cutaneous trunci reflex cut-off and spinal cord injury severity was tested using a Mann–Whitney U test. Results: Cutaneous trunci reflex cut-off was evident in 33 (80%) of dogs. The cut-off level was 0 to 4 vertebrae caudal to the maximal spinal cord lesion in all dogs. In 16 (48·5%) dogs the cut-off was either 2 or 3 vertebrae caudal to the lesion. The presence of a cut-off significantly correlated with increasing severity (P=0·0001). Loss of the reflex occurred at less severe grades than loss of ambulation and in dogs with ambulatory paresis it was significantly (P=0·0084) associated with increasing severity. Clinical Significance: The cutaneous trunci reflex allows localisation of thoracolumbar spinal cord lesions within four vertebrae and facilitates clinical segregation of dogs with ambulatory paresis into mild and severe categories