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Thrombocytopenia is a somewhat rare condition in horses, which is defined as having a low platelet count. It is associated with horses having s platelet count of less than 100 x 103 per microliter. It was found to occur in approximately 1.5% of hospitalized horses in one study conducted. It is generally caused by one of two reasons:
  • Disorders which result in bone marrow not being able to produce enough platelets
  • Conditions where platelets are used up or destroyed at a faster rate then they normally would.
Conditions which are associated with horses having low platelet counts include:
  • Idiopathic thrombocytopenia (ITP)
  • Certain drugs and antibiotics, colchicine and indomethacin, quinidine, hydralazine, H2-blocking agents, tolbutamide, isoniazid, and thiazide diuretics, are a few that have a history of association with drug-induced decrease in platelet counts.
  • Leukemia, lymphoma, or other cancers that may have spread to the horse's bone marrow.
  • Platelet consumption is seen in horses suffering from disseminated intravascular coagulation (DIC), thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS).
  • Chemotherapy or radiation therapy, which may affect the bone marrow's ability to produce platelets
  • Autoimmune disorders
  • Viral infections
  • Aplastic anemia
  • Exposure to toxic chemicals, such as pesticides, arsenic, or benzene
  • Sepsis, especially if associated with an infection with a Gram-negative bacteria
  • Symptoms

    Blood present in the mouth and gums
    Horse appears to bruise more frequently
    Frequent nosebleeds


    • History
    • Clinical signs
    • CBC



    It is important to determine the cause
    Supportive careAdministration of fresh frozen plasma and heparin


    The outcome depends on the disorder causing the low platelet counts.

    Scientific Research

    General Overviews

    Risk Factors

    • History of recent snake bite