Hemorrhage and blood loss-induced anemia associated with an acquired coagulation factor VIII inhibitor in a Thoroughbred mare.

The research article discusses the diagnosis, treatment and successful management of a rare bleeding disorder known as acquired hemophilia A in a 23-year-old Thoroughbred mare.

Background

• The horse, upon examination, showed signs of severe anemia due to blood loss which included a high heart rate, pale gums, reduced blood flow and a large swelling observed in the right flank of the horse.
• Further ultrasonographic examination revealed the swelling to be a massive hematoma (blood-filled swelling) in the body wall leading to bleeding within the abdomen.

Diagnosis

• Results from coagulation tests showed a prolonged activated partial thromboplastin time (aPTT), indicating an issue with blood clotting.
• The aPTT score was significantly higher than the normal range, leading researchers to further examine clotting factors in the mare’s blood.
• The mare was found to have seriously deficient levels of Factor VIII, which contributes to normal blood clotting.
• Considering the mare’s age, the sudden onset of the bleeding disorder, and specific tests assessing Factor VIII inhibitory activity in the plasma, the horse was diagnosed with acquired hemophilia A. This is a rare condition caused by the idiopathic (unexplained) development of inhibitory antibodies against Factor VIII.

Treatment and Outcome

• The mare was treated initially with transfusions of fresh whole blood and fresh-frozen plasma, to supplement the deficient Factor VIII and to correct anemia.
• Next, an immunosuppressive treatment was introduced comprising of dexamethasone and azathioprine, to counter the activity of the inhibitory antibodies that were preventing Factor VIII from performing its normal function.
• The treatment was successful as observed in the normalized Factor VIII levels, resolved signs of coagulopathy (bleeding disorder), and a decrease in the inhibitory antibody titer (measurement of the concentration of the antibodies).
• The mare exhibited sustained remission for at least a year following the treatment with no signs of recurrence of the disease.

Conclusions

• The study concludes that horses can develop acquired hemophilia A due to the emergence of inhibitory antibodies against Factor VIII..
• The case study demonstrates how combining transfusion of fresh whole blood and fresh-frozen plasma, along with administration of immunosuppressive drugs, can effectively treat the condition and induce sustained remission.