Prothrombotic events in the prodromal stages of acute laminitis in horses.

The research explores the prothrombotic changes in horses during the early stages of carbohydrate-induced laminitis, a painful condition affecting horse’s feet. The findings suggest that platelet survival reduces in the first six hours after the onset of laminitis, although there is no detected systemic activation of the coagulation system.

Study Objectives and Methodology

• The study aimed to identify the prothrombotic events (involved in blood clotting) during the initial stages of carbohydrate-induced laminitis in horses.
• To assess the hemostatic alterations (which impact blood clotting). Several variables were measured. These included platelet counts, platelet survival, one-stage prothrombin time, activated partial thromboplastin time, and monocyte procoagulant activity.
• The researchers also investigated the thrombosis (clotting) in the hoof wall vessels through contrast arteriography (a way to visualize blood vessels in radiographic images) and histologic examination.

Key Findings

• Of the five tested horses, lameness was observed in four between 28 and 52 hours after carbohydrate administration.
• The mean platelet count, although lower in horses affected by laminitis during the early stages, was not statistically significant compared to control horses.
• However, by six hours after carbohydrate administration, platelet survival in laminitis-affected horses decreased, which was significantly less than in control horses.
• Arteriography indicated a significant reduction in blood supply to the hooves in laminitis-affected horses.
• Microthrombi (tiny clots) were discovered within the laminar dermis (a layer of skin) of two out of four affected horses, but they didn’t observe significant changes in prothrombin time.
• The changes in activated partial thromboplastin time (a test measuring blood clotting) were minor and only present at the onset of lameness. Also, significant changes in monocyte procoagulant activity (a part of the body’s response to injury that might cause thrombosis) were not observed.
• No detectable plasma endotoxin-like activity (possible cause of laminitis) was found in horses affected by laminitis.

Conclusion

• The study concludes that while platelet survival decreased with the onset of carbohydrate-induced laminitis, no systemic activation of the coagulation (clotting) system was observed. This indicates that prothrombotic events may occur locally within the affected laminae early on, even before systemic coagulation factors are activated.