[Growth of the hoof horn in horses with chronic laminitis].

The research investigates the relationship between rotation or sinking of a horse’s pedal bone, known as third phalanx (P3), and changes in the growth of the hoof horn in horses chronically afflicted with laminitis. The findings suggest a strong correlation and propose resection of the dorsal hoof wall as a possible treatment with horses showing at least 8° of P3 rotation.

Study Objectives and Methods

• The study’s main objective was to uncover whether there’s a link between the rotation or sinking of the P3 and the growth changes in the hoof horn of horses suffering from chronic laminitis.
• The research utilized 117 hooves from horses either euthanized or slaughtered due to chronic laminitis. Data was gathered from radiographs to measure the rotating angles towards palmar/plantar and medial/lateral directions and the sinking of P3.
• Specific distances were calculated on the dorsal hoof wall as well as in the heel to evaluate the growth of a hoof horn. Additionally, the path of the horn tubes was estimated based on saw cuts of the hooves.

Results

• The research found that a rotation angle of about 8° was a significant predictor of a shift in the direction of hoof horn growth at the dorsal and lateral hoof wall.
• A clear connection was revealed between the rotation angle of P3 and the growth length of the hooves. Larger angles could result in a greater disruption of the dorsal horn growth, while the palmar/plantar horn growth seemed unaffected.
• Interestingly, the study found no link between medial/lateral rotation of the pedal bone and the horn length. Also, changing the direction of the horn tubes may decrease the externally visible growth length of a chronic laminitic hoof.
• The study concluded that in chronically laminitic horses, a significant difference needs to be made between the externally visible length of the hoof and actual growth of the horn. Wrinkle formations in the horn tubes on the dorsal hoof wall reduced the visible wall length.

Implications and Conclusions

• The research concludes that the direction change caused by rotation or sinking of P3 could be influencing the growth patterns of the hoof horn in chronic laminitic horses.
• The study emphasizes that horses with moderate laminitis showed the horn tubes on the dorsal hoof wall lying in folds, which drastically reduced the visible growth length.
• Despite revealing that the overall volume of horn produced is about the same on the dorsal hoof wall and in the heel, the externally visible length can be an unreliable representation of growth due to these changes in the horn direction.
• A significant recommendation from the study is the possibility of the dorsal hoof wall’s resection as a potential treatment approach for chronic laminitic horses showing a P3 rotation of at least 8°.