Most fractures are due to road traffic accidents (RTA) and most occur in the thoracolumbar spine. Associated injuries are significant: 34% of dogs with lumbar fractures have cardiopulmonary injuries such as pneumothorax and pulmonary contusions; 48% have other fractures, of which pelvic fractures were most common and approximately 23% have abdominal injuries.
Neurological deficits may not correspond to the site of the fracture due to the associated cord oedema, haemorrhage or myelomalacia. Repeat examinations at least twice daily, paying particular attention to the quality of spinal reflexes and muscle tone in the limbs, any ‘cut-off’ in the cutaneous trunci reflex, and movement of the thorax. An UMN paraplegia changing into LMN paraplegia indicates that the lesion is extending into the lumbosacral intumescence. Cranial extension of the lesion within the thoracic spinal cord will not change the hindlimb reflexes or muscle tone but the cutaneous trunci reflex will be abnormal and thoracic movement will weaken. Ascending myelomalacia is usually recognized before the animal dies of respiratory failure. Schiff–Sherrington syndrome occurs with sudden onset T3–L3 spinal cord lesions and may give the impression of a UMN cervical lesion.
Assessing the degree of voluntary motor function is difficult when the animal is kept immobile to stabilize the fracture site. Calling the animal or offering food may induce voluntary movement in limbs. Pelvic fractures add to the animal’s immobility.
The dog was mentally alert with hindlimb paralysis, normal to slightly increased hindlimb reflexes, no pain perception in either hindlimb, absent cutaneous trunci reflex caudal to the scapulae and absent pain perception caudal to the scapulae. The bladder was large and difficult to express. Respiratory movements were chiefly abdominal.
Positioning must reflect the neuroanatomical diagnosis (Fig. 42.1). Trauma, infection and neoplasia may produce multifocal lesions which require the whole spine to be radiographed. Assess changes in vertebral shape, density, alignment and surrounding soft tissues. Always check the dorsal articular facets as these will remain fractured even if vertebral bodies realign after the trauma (Fig. 42.2 and see Table 42.1).