Corticosteroid-responsive thrombocytopenia in two beef cows.

Corticosteroid-responsive thrombocytopenia was identified in 2 beef cows. Clinical findings in 1 cow included hematoma formation, petechiation of mucous membranes, anemia, and persistent thrombocytopenia. Cow 2 was in its fourth month of gestation and had epistaxis, nasal mucosal petechiation, anemia, and thrombocytopenia. Treatment included parenteral administration of corticosteroids at immunosuppressive dosages. Cow 1 had a history of chronic hematoma formation and responded to long-term treatment with dexamethasone, but it relapsed 2 months after treatment was discontinued. Cow 2 had acute onset of clinical signs, responded to short-term treatment with prednisone, delivered a full-term, healthy calf, and remained clinically normal for at least 1 year after treatment was completed. Reported causes of thrombocytopenia in ruminants were ruled out or seemed unlikely; a definitive cause for thrombocytopenia in the 2 cows could not be established.