# Effects of Soft Ground on Paw Center of Pressure Metrics in Dogs During Walk and Trot

## TL;DR

This study shows how dogs adjust their balance and paw pressure when walking and trotting on surfaces of different softness, helping improve physiotherapy for dogs.

## Contribution

The study introduces paw center of pressure (pCOP) analysis as a sensitive method to detect balance adjustments in dogs on compliant surfaces.

## Key findings

- Dogs reduce pCOP displacement on softer surfaces, especially during trotting.
- pCOP metrics are more sensitive to surface compliance than vertical ground reaction forces.
- Adaptations are more pronounced in front limbs during walking and at faster speeds.

## Abstract

Physiotherapy in dogs often includes exercises on soft or unstable surfaces to improve balance, body awareness, and coordinated movement. Despite their frequent use, little is known about how dogs adjust their posture when moving on surfaces of different softness. This study investigated how healthy adult dogs adapt their walking and trotting patterns when moving across surfaces with increasing compliance. Fourteen dogs walked and trotted over a pressure-sensitive walkway covered with mats of different thicknesses. This method allowed the assessment of how body weight was distributed and how the center of pressure beneath each paw moved during ground contact. The overall forces applied to the ground remained largely unchanged across surfaces. However, the movement of the pressure point within the paw decreased on softer surfaces, particularly during trotting. This indicates that dogs actively adjust their posture to maintain stability when moving on compliant ground. These adaptations were more pronounced at faster speeds and were mainly observed in the front limbs during walking. The findings demonstrate that measuring pressure distribution within the paw is a sensitive way to detect subtle balance adjustments. This knowledge may support veterinarians and animal physiotherapists in objectively evaluating and optimizing rehabilitation exercises for dogs.

Physiotherapeutic interventions in dogs frequently incorporate compliant surfaces to improve postural stability (PS), proprioception, and limb coordination; however, objective assessment of surface-related locomotor adaptations remains limited. This study investigated the effects of walking on surfaces with increasing compliance on PS in healthy adult dogs using paw center of pressure (pCOP) analysis. Fourteen orthopedically and neurologically sound dogs were assessed at walk and trot on a pressure-sensitive walkway under four surface conditions: a standard rubber mat (0.1 cm) and three yoga mats of increasing thickness (0.5 cm, 0.8 cm, and 1.0 cm). Vertical ground reaction force (vGRF) and pCOP parameters were recorded and analyzed for each limb. vGRF parameters were largely unaffected by surface conditions. In contrast, several pCOP metrics, including pCOP radius, craniocaudal displacement, and mediolateral displacement, showed a significant decrease with increasing surface compliance. These effects were more consistent and widespread during trot, whereas during walk changes were primarily observed in the forelimbs. The findings indicate that dogs adapt to increased surface compliance by reducing pCOP displacement, likely reflecting active postural stabilization strategies. While vGRF parameters appeared insensitive to these adaptations, pCOP measures proved more sensitive in detecting subtle neuromuscular adjustments. These results highlight the potential value of pCOP analysis for evaluating functional adaptations during physiotherapeutic interventions in canine rehabilitation.