Expression of the cyclooxygenase isoforms in the prodromal stage of black walnut-induced laminitis in horses.

This research study investigates the role of cyclooxygenase (COX)-1 and COX-2 enzymes in the early stages of horse laminitis, a disease affecting the feet, which was artificially induced using black walnut extract (BWE). The study found increased expression of COX-2, but not COX-1, suggesting potential therapeutic uses of COX-2 inhibitors.

Research Methodology

• Researchers compared the mRNA expressions of cycooxygenase (COX)-1 and COX-2 in the foot tissue, or digital laminae, of healthy horses and horses in the early stages of laminitis.
• Laminitis was induced in horses by administering Black Walnut Extract (BWE).
• mRNA samples were extracted from the digital laminae of both healthy control horses and those affected by laminitis.
• The team collected laminae samples from anesthetized horses prior to their euthanasia.
• They evaluated COX-1 and COX-2 mRNA expression in the tissue from both control and affected horses using real-time quantitative polymerase chain reaction (PCR) techniques.

Research Findings

• There was significant upregulation, or increased production, of COX-2 mRNA in the group treated with BWE compared to the control group.
• Contrarily, the level of COX-1 mRNA expression did not significantly differ between the control and BWE-treated horses.
• Interestingly, despite all BWE-treated horses displaying leukopenia, or a decrease in white blood cells, there were marked differences in the increase of COX-2 mRNA expression among these horses, ranging from no increase to a 30-fold increase.

Conclusions and Implications

• The findings of the study suggest a significant increase in COX-2 mRNA expression during the developmental stages of laminitis without any notable change in the production of the COX-1 isoform.
• This could indicate a potential therapeutic route, justifying the aggressive use of nonsteroidal anti-inflammatory drugs (NSAIDs) in horses at risk of developing laminitis.
• Given these results, the research team recommends further investigation into the clinical value of selective COX-2 inhibitors as a potential treatment for laminitis in horses.