Morphology: red blood cells with a clear crescent-shaped area along one side of the periphery. Formed by the fusion of two layers of oxidized cell membrane with no hemoglobin in between.

Commonly seen with: Heinz bodies

Clinical relevance: indicates oxidant injury to red blood cells. Oxidant injury may result from certain drugs (propofol and acetaminophen in cats) or from toxins (onions, red maple leaves in horses, zinc in dogs, copper in sheep, anticoagulant rodenticide in dogs, and skunk musk in dogs). Oxidant injury may also result from certain diseases (lymphoma and diabetes mellitus in dogs).