This study will test the effectiveness of four antioxidants against Heinz bodies in cats. Heinz bodies are clumps of damaged hemoglobin inside red blood cells that result from oxidative damage and cause anemia. Cat hemoglobin is uniquely sensitive to oxidative damage, and Heinz bodies are readily caused by oxidant drugs, dietary ingredients (fish, onion) and diseases such as diabetes. Veterinarians face a difficult dilemma when presented with a cat with many Heinz bodies but no history of exposure to oxidant drugs. Because the exact source of oxidative stress often cannot be determined, practitioners may not be sure whether dietary change or treatment of underlying disease will alleviate the Heinz body formation. Left untreated, Heinz bodies may persist or worsen and are likely to increase the severity of anemia in an already ill patient. Little research has been done in cats on the therapeutic efficacy of antioxidants. The results of this study will be invaluable for ascertaining the rational use and selection of antioxidants in the treatment of Heinz body anemia in cats.