Cervical spinal kinematics: a comparison between foals and adult horses.

A photographic method was used to measure axial rotation, dorsoventral flexion and extension and lateral bending at each intervertebral joint complex from the occiput to the first thoracic vertebra in spinal segments from 19 foals under 12 months of age and 14 horses over three years of age. Comparisons between the two groups showed that there was a general reduction in cervical spinal mobility with age. For the three types of movement at the eight joints tested, adults' mobility exceeded that of foals in only three cases (axial rotation and lateral bending at the A-O joint, and lateral bending at C7-T1). These differences were not significant (P greater than 0.05). In the remaining 21 cases the amplitude of movement was greater in the foals, the differences being significant (P less than 0.05) in 16 cases. With regard to overall mobility of the cervical spine the foals exceeded the adults by 17.3 per cent for axial rotation, 22.0 per cent for dorsoventral flexion and extension and 18.7 per cent for lateral bending.