Suspected immune-mediated megakaryocytic hypoplasia or aplasia in a dog.

Megakaryocytic hypoplasia or aplasia causing thrombocytopenia was diagnosed in a 3-year-old Miniature Poodle with scleral hemorrhage, melena, ecchymoses, and blood-loss anemia. Immunosuppressive, cytotoxic, and lithium carbonate therapy resulted in successful correction of the dog's disease. It is important to recognize megakaryocytic hypoplasia or aplasia as the cause of thrombocytopenia, since the response to therapy will be slower when there is stem cell injury.