Development of postural balance in foals

This study used stabilographic analysis to measure and describe changes in stability during standing in foals from birth to 5 months of age. Stabilographic analysis was performed on newborn foals immediately after first suckling then daily until 1 week of age, weekly until 1 month of age and monthly until 5 months of age. Ground reaction force (GRF) data were collected for periods of 8s with the foal standing on one or two force plates recording at 1000 Hz. Stabilographic variables describing the amplitude, velocity and frequency of center of pressure (COP) movements were derived from the GRF data. Amplitudes, which were initially larger in the craniocaudal direction, decreased over time in both directions, with craniocaudal amplitude becoming smaller than mediolateral amplitude by 1-2 months of age. At birth, COP velocity was larger in the craniocaudal direction, but decreased rapidly to become smaller than mediolateral velocity by 3 months of age. Mean frequency at birth was higher craniocaudally, but became similar in both directions at 2 months of age. The rapid reductions in craniocaudal amplitude and velocity were thought to reflect improvements in strength and coordination of the flexor/extensor musculature. Newborn foals splay their limbs to compensate for poor control of the abductor/adductor musculature and, after the limbs assumed a vertical posture, mediolateral sway velocity increased.