Noninvasive photoelastic method to show distribution of strain in the hoof wall of a living horse.

The research article presents the application of a photoelastic method, typically used in industry materials testing, on a living horse’s hoof to observe the distribution of strain or change in length per unit length when loaded compared to its unloaded state.

Methodology

• The researchers adapted a photoelastic method, a technique used for materials testing in industries, to study a horse’s hoof. The photoelastic effect refers to the phenomenon where a material exhibits different colors when it is under strain and observed under polarized light. These color changes are known as fringes.
• They applied this method to analyze the distribution of strain, which refers to the change in length per unit length in the material of the loaded hoof wall compared to the unloaded state, through the hoof wall in living horses.

Strain Derivation

• The appearance of colored fringes in the photoelastic plastic indicates the presence of strain gradients. This occurs when there are differences in strain between adjacent sites in the hoof.
• The strain distribution was then observed in both the shod and unshod hoof wall of the front hooves in six sound horses, which signify healthy horses having hooves that look ‘good’ visually.

Results

• No significant differences in strains were apparent across the hoof walls of the sound horses when they were standing normally. This suggests that the pressure or force exerted on the hoof during regular standing is evenly distributed.
• The method revealed steep strain gradients in hooves associated with defects, specifically, cracks, unstable nail holes, and long toes. The presence of these defects might lead to uneven pressure distribution when the horse is standing, walking, or running, causing certain areas of the hoof to bear more strain than others.
• The method was also tested on an unsound horse with hoof cracks. The distribution of strain was different than the sound horses, indicating the method’s critical potential for detecting hoof health issues.

Conclusion

• The researchers successfully demonstrated that the photoelastic method could be used to visualize the distribution of strain across the hoof wall of a living horse.
• This study offers valuable insights that could be useful in the fields of equine medicine and care, providing a non-invasive, direct method to detect potential hoof health issues and observe the effects of different shoeing techniques on the strain distributions in the horse’s hoof.