Light and electron microscopy of keratinization in the laminar epidermis of the equine hoof with reference to laminitis.

The study investigates the role of keratinization in the formation of the hoof wall in horses, specifically focusing on the laminar epidermis. Findings contradict the previously held belief that the secondary epidermal laminae had a non-germinative role in the process.

Study Methodology

• Hooves taken from 14 clinically normal horses, aged between 6 months and 15 years, were studied.
• Advanced techniques including light and electron microscopy and immunofluorescence were utilised.
• The laminar epidermis or the epidermis parietis of these hooves was the primary focus of the investigation.

Key Observations

• The process of keratinization in the secondary epidermal laminae contributed largely to the formation of the hoof wall, with the white line showing its contribution to be about 20% of the overall thickness.
• The keratinized, primary epidermal laminae grew to a height of 4 mm, a large part of this obscured due to the basal portion being embedded in the cap horn epidermis.

Conclusions

• By evaluating the structural changes during keratinogenesis and quantifying the contribution of the laminar epidermis to the formation of various portions of the hoof, the researchers were able to debunk the sterile bed concept.
• This old belief put forth that the secondary epidermal laminae did not have a role in-growing or simply had a non-germinative role.
• In contrast, the current study proposed that this is untrue, noting that the secondary epidermal laminae play a significant role in hoof formation.