Postural stability in the dog

Abstract

Positional stability in quietly standing dogs has been evaluated in terms of force records from individual feet and the position of the center of gravity. All four dogs carried approximately 60% of their total weight on their anterior feet and roughly 50% of their weight on each side. Within-trial variations from the mean of the fraction of total weight borne on any one foot ranged from 0.3 to 4.5% with a mean of 1.4%; between-trial variability ranged from 1.1 to 2.7%. Continuous movement of the center of gravity occurred within an area measuring approximately 1.5 cm on a side. Shifts in weight distribution within and between trials occurred in a variety of patterns which could be described in terms of the behavior of pairs of transverse, longitudinal, and diagonal couples. Preliminary observations of the reactions to a sudden disturbance confirm the hypothesis that quiet stance is accomplished through central nervous regulation. It is concluded that the trained dog behaves with a sufficient level of predictability to permit its use as a subject in a further examination of the postural control system.