Disease-specific changes in equine ground reaction force data documented by use of principal component analysis.

The study explores the effectiveness of using a force plate, a device that measures the ground reaction force exerted by a moving subject, for diagnosing locomotor abnormalities in horses. Particularly, it’s focused on diseases like navicular disease that lack specific diagnostic criteria. This was determined through experiments on thoroughbred horses and the analysis of the recorded ground reaction force patterns.

Research Method

The study involved three groups of thoroughbred horses:

• Group A consisted of 17 horses presenting no observable locomotor abnormalities.
• Group B included 6 horses with superficial digital flexor tendon injury.
• Group C included 8 horses suffering from navicular disease.

The ground reaction force patterns of all groups were recorded using a force plate while they were trotting. The peak limb vertical force and force/time curve parameters were drawn from four points identified at the beginning and the end of vertical and craniocaudal horizontal plots.

A Principal Component Analysis (PCA), commonly used for dimensionality reduction in data, was conducted on the starting and ending stride data of group A horses. The first two principal components were represented graphically. The rotation matrices obtained from the PCA were then applied to the equivalent data of group B and C horses.

Research Findings

The results showed that peak vertical force (PVF) asymmetry could not distinguish between groups A, B, and C. However, the values for horses in group B were significantly outside the average range of group A, specifically in the beginning of stride phase variables.

The data points for group B were within the range of group A for end of stride phase variables. For the horses in group C showing symptoms of navicular disease, the values were significantly outside the range of group A for both beginning and end of stride phase variables.

Conclusions

The researchers concluded that performing a PCA of force/time data provides a sensitive method to evaluate the force/time curve associated with specific injury/disease processes like superficial digital flexor tendon injury and navicular disease. The study found that horses change the way they bear weight in unique ways when they have such diseases, and that analysis of these changes could make the force plate an important tool for both prognosis and diagnosis of such conditions in horses.