Interday variation in vertical ground reaction force in clinically normal Greyhounds at the trot

Area of Science:

• Canine biomechanics
• Veterinary orthopedics
• Animal locomotion analysis

Background:

• Vertical ground reaction force (vGRF) variables are critical for assessing canine locomotion and lameness.
• Interday variation in vGRF measurements can affect the reliability of research findings.
• Understanding day-to-day variability is essential for accurate interpretation of canine gait data.

Purpose of the Study:

• To quantify the extent of interday variation in vGRF variables in clinically normal dogs.
• To determine the impact of day-to-day changes on peak vertical force (PFz) and impulse (IFz) in canine hind limbs.
• To assess the significance of within-dog variation across consecutive measurement days.

Main Methods:

• 52 clinically normal Greyhounds were analyzed.
• vGRF variables (PFz and IFz) were measured from hind limbs during trotting over a force platform.
• Data were collected on three consecutive days, with variance components estimated using maximal likelihood and ANOVA.

Main Results:

• Significant interday variation in PFz, IFz, or both was observed in 29 out of 52 dogs.
• ANOVA confirmed that the day-within-dog interaction was a significant factor for PFz and IFz.
• A substantial portion of dogs exhibited day-to-day differences in vGRF measurements.

Conclusions:

• Interday variation is a significant factor that must be considered in statistical models analyzing canine vGRF data.
• A statistical model incorporating accommodation for interday variation is proposed.
• Researchers should identify and account for factors contributing to variation, including interday effects, in their data analysis.