Trauma in a Foal

History. Distraught owners call you about their 4-month- old Tennessee Walking Horse colt. He appeared normal this morning when they let him out to pasture with his mother, but later this afternoon, the mare and the foal did not come in to be fed.

Clinical Examination. The foal appears to be responsive but in great pain and unable to rise. Temperature, pulse, and respirations are all mildly increased. There appears to be a swelling along the cervical (neck) area in the region of Cl -C3. The swelling is hard (bone) and has some fluid (inflamma­tion) as well. There is some crepitus in the area of the swelling (possible fracture site). The foal displays no other areas of swelling or trauma. Neurological examination reveals normal cranial nerves. In the front limbs the biceps and triceps reflexes seem increased on both sides. Deep pain is present, and cutaneous sensation is increased bilaterally. In the hind limbs the femoral, sciatic, and tibial responses are increased.

Comment. Although it is difficult to localize a fracture definitively, based on history and physical examination a frac­ture seems likely. The fracture appears to be in the region of Cl-C3. Radiographs would be ideal to make a definitive diag­nosis. On neurological testing of the biceps, triceps, sciatic, femoral, and cranial tibial responses, all assess segmental reflex arcs. Because of a high cervical fracture, the descending motor tracts that supply both the thoracic and the pelvic limbs are affected. From point of initiation, the segmental reflexes tested involve the muscle spindles, which detect stretch, followed by sensory fibers in the peripheral nerves, the dorsal root and its ganglion, and the central branches of the sensory fibers pro­jecting onto the ventral horn cell of the same spinal segment. The efferent pathway involves the ventral horn cell (lower motor neuron), followed by the ventral root, motor fibers in the peripheral nerve, neuromuscular junction, and then the myofibers being tested. The presence but exaggeration of the segmental reflexes reflects a change in the modulation of these reflexes by the damaged descending motor tracts that pass through the area of the lesion.

Treatment. The prognosis for this foal is poor. Based on the physical examination and clinical signs, a fracture is likely, and there is little hope for recovery. The complications asso­ciated with trying to manage a foal as the fracture heals are enormous. The fracture may not heal, and the foal could have severe residual neurological deficits. In most cases, these foals are euthanized fairly quickly because of the poor prognosis.