Thrombelastographic characterization of coagulation/fibrinolysis in horses: role of carboxyheme and metheme states.

This research explores the impact of carboxyheme and metheme states on blood clotting and clot breakdown in horses, particularly in relation to gastrointestinal illnesses. It suggests that the balance of carbon monoxide and nitric oxide can influence whether blood is more prone to clotting or clot dissolution, with an overabundance of nitric oxide potentially leading to a hypocoagulable (low clotting) and hyperfibrinolytic (high clot dissolution) state.

Background

• Carboxyheme and metheme states are conditions which affect blood coagulation (clotting). These states are influenced by the presence of carbon monoxide or nitric oxide.
• Previous research has shown that these gases can be produced in higher quantities in inflammatory disorders of the gastrointestinal tract.
• Horses are known to suffer from thrombotic (clotting) and coagulopathic (bleeding) complications during acute gastrointestinal disease.

Methodology

• Citrated plasma was collected from 14 healthy mares and three horses with enteritis.
• The effect of carboxyheme (induced with CORM-2) and metheme (induced with phenylhydroxylamine, PHA) states, with and without tissue type plasminogen activator (an enzyme that aids in clot breakdown), was then observed.

Results

• The study found that inducing a carboxyheme state in normal horses did not significantly speed up clot growth and only slightly increased clot strength.
• In contrast, the metheme state, which is associated with an increase of nitric oxide, resulted in a decrease in clot formation and strength.
• During fibrinolysis (clot breakdown), the carboxyheme state decreased the onset and speed of the process, while the metheme state increased both.

Implications

• The results suggest a carbon monoxide-dominant moderation of hemostasis (the process which causes bleeding to stop) in healthy horses.
• However, an intensification of acute gastrointestinal disease was linked to a probable nitric oxide-mediated, metheme state-induced hypocoagulable/hyperfibrinolytic state. This means that an abundance of nitric oxide might promote a state where blood is less prone to clot and more prone to dissolve existing clots.
• The findings suggest that further research is needed to investigate the role of carbon monoxide and nitric oxide in equine diseases related to blood clotting and bleeding.