Different strategies of bipeds and quadrupeds to maintain postural stability- a comparison of healthy humans and dogs via static posturography

Postural stability (PS) is the ability to maintain balance through the integration of sensory inputs from the proprioceptive, visual, and vestibular systems. This study compared PS between healthy adult humans and dogs using static posturography and investigated the effect of blindfolding on PS. Twenty-two healthy young adults and twenty-two healthy young pet dogs were assessed using a pressure measurement platform under eyes open and eyes closed conditions. The Romberg indices of 5 center of pressure (COP) parameters were calculated: mediolateral displacement (RI MLD%), craniocaudal/anteroposterior displacement (RI CCD%), COP length (RI L%), average speed (RI AS), and support surface (RI SS%). Significant differences were observed between humans and dogs for RI CCD%, RI L%, and RI AS. Humans exhibited greater reliance on visual input for balance, indicated by higher RI values for these parameters, suggesting increased instability when blindfolded. In contrast, dogs showed lower RI values, indicating less reliance on vision and more stable postural control. The lack of significant differences in RI MLD% and RI SS% suggests similar mediolateral and support surface compensatory mechanisms between species. These findings reveal fundamental mechanistic differences in how balance is maintained between the two species.