Drug-associated blood cell dyscrasias.

Many therapeutic drugs have been associated with hematologic adverse drug events (ADEs) in animals. Some drugs, notably chemotherapeutic agents and oxidant compounds, cause dose-dependent bone marrow suppression, while others induce idiosyncratic ADEs. Major mechanisms associated with ADEs include immune- or oxidant-mediated destruction of blood cells and toxic bone marrow injury. General classes of drugs that can cause idiosyncratic ADEs include estrogenic compounds, NSAIDs, antibiotics, antifungals, antithyroid drugs, anticonvulsants, antiparasitics, and cardiac drugs. ADEs associated with chemotherapeutic agents, phenylbutazone, phenobarbital, propylthiouracil (in cats), methimazole (in cats), and azathioprine occur frequently enough to warrant performing periodic complete blood counts during the course of treatment.