Changes in kinematic variables observed during pressure-induced forelimb lameness in adult horses trotting on a treadmill.

The research investigates the kinematic changes caused by induced pressure on different parts of the horseshoe. The findings suggest that different groupings of altered locomotive patterns in adult Quarter Horses can potentially serve as indicators of localised lameness, enabling more precise diagnosis and treatments.

Research Methodology

• The study’s subjects were ten adult Quarter Horses. The researchers used a specialized horseshoe that created pressure either on the frog (a shock-absorbing structure on the bottom of a horse’s foot) or on the toe region of the hoof.
• Kinematic analysis was performed before and after two levels of frog pressure and after a singular level of toe pressure. This data was collected as the horses trotted on a treadmill, ensuring consistent and measurable conditions.
• The stride displacement (distance covered per stride), stride duration (time between strides), joint angles, head movements, and forelimb movement were some of the variables analyzed to identify potential signs of lameness or discomfort.

Findings

• The first level of frog pressure resulted in decreased extension of the fetlock joint (roughly analogous to the human ankle) during stance (the phase of the stride where the horse’s foot is in contact with the ground), increased asymmetry, and increased vertical head movement.
• The second level increased these changes and also caused decreased stride duration and carpal joint extension during stance, as well as increased relative stance duration.
• Toe pressure resulted in similar changes and also caused a shift in the timing of maximum fetlock joint extension to occur before midstance, the point of maximum hoof height to occur nearer to midswing, and increased forelimb protraction.

Conclusion and Clinical Implications

• The study concludes that decreased fetlock joint extension during stance, increased head vertical movement, and asymmetry are sensitive indicators of forelimb lameness.
• Decreased stride duration, increased relative stance duration, and decreased carpal joint extension during stance, while not as specific, may act as general albeit less sensitive lameness indicators.
• Specific alterations including increased forelimb protraction, altered hoof flight pattern, and premature maximum fetlock joint extension might be specific lameness indicators for the toe region.
• Overall, the research suggests that detailed observation of the forelimb movement might help clinicians differentiate between heel and toe lameness in horses, thereby allowing for more localized and efficient treatments.