Equine Hoof Canker: Cell Proliferation and Morphology.

This research investigates the cellular changes that occur during the development of hoof canker in horses. It focuses on the patterns of cell proliferation and the morphological changes in the hoof canker tissue, helping to reveal increased protein expression and significant alterations in cell differentiation as key factors in the disease’s progression.

Background

• Hoof canker is a progressive condition affecting the hooves of horses. It involves the absence of epidermal cornification and increased growth of the dermal papillary body, part of the skin within the hoof. Despite this understanding, no detailed research on the type of growth activity had previously been conducted.

Methodology

• The study’s goal was to identify the specific patterns of cell growth and evaluate the morphological changes in hoof canker tissue. This involved comparing tissues from 19 horses with canker, removed during surgical procedures, with post-mortem tissues from 10 healthy hooves.
• Light microscopy was used to check for observable morphological changes, which were then semi-quantitatively assessed and graded according to their severity.
• The researchers used immunohistochemistry – a technique using antibodies to detect particular proteins or antigens in cells of a tissue section – focusing on anti-PCNA and anti-Ki67, to evaluate cell proliferation.

Findings

• Five major morphological changes were found in the canker tissue – lacunae, vacuoles, giant cells, hemorrhage, and inflammation – none of which were present in the control tissue.
• Keratinocytes (the predominant cell type in the epidermis, the outermost layer of the skin) in canker tissue showed a characteristic koilocytotic appearance that differs from normal.
• The study found increased levels of PCNA protein expression in keratinocytes and fibroblasts (cells that produce collagen and other fibres) in canker tissue compared with the control tissue. This is notable, as PCNA is often used as a marker of cell proliferation.
• In contrast, keratinocytes in the control tissue had higher levels of Ki67 – another marker of cell proliferation – compared to those in canker tissue. Meanwhile, dermal fibroblasts in both groups showed approximately equal levels of Ki67. This suggests that these cells in cankerous and healthy hooves have similar proliferative activity.

Conclusion

• The findings contradict previous reports suggesting increased proliferative activity in the dermal papillary body is associated with hoof canker. Instead, elevated levels of PCNA protein expression and morphological abnormalities highlight the dysregulation of keratinocyte differentiation as a key aspect of the disease.
• Therefore, future studies and treatment strategies should consider this aspect while dealing with hoof canker in horses.