A case of thrombocytopenia in a Collie dogIdiopathic thrombocytopenia, the most common cause of the hemorrhagic syndrome in the dog, was diagnosed in an adult male Collie. The bleeding tendency was manifested by anemia, ecchymotic hemorrhages, melena and bilateral epistaxis. Hook-worms increased the anemia. The clinical diagnosis was confirmed by a reduced platelet count. Prednisone was the specific treatment.