Allium species include onions, garlic and leeks. These plants contain a variety of organosulphoxides. Metabolism of the organosulphoxides causes oxidative damage to haemoglobin which results in sulphaemoglobin and this precipitates, aggregates and binds to cell membranes forming Heinz bodies. Eccentrocytes form due to direct oxidative damage to cell membranes. The main toxic compound n-propyl disulphide also depletes the enzyme glucose-6-phosphate dehydrogenase (G6PD) within erythrocytes which renders them more susceptible to oxidative damage. The formation of eccentrocytes and Heinz bodies increases cell fragility and extravascular haemolysis. Erythrocytes containing Heinz bodies are removed from the circulation by the recticuloendothelial system, thereby inducing anaemia.

There are cases of Allium poisoning in cat and dogs but two recent reports describe poisoning in exotic species. A South American coati (Nasua nasua) developed Heinz body anaemia after ingestion of leeks (Allium ampeloprasum) over 2-5 days. He recovered with supportive care and a blood transfusion. A group of tortoises including one Aldadra giant tortoise (Aldabrachelys gigantea) and three African spurred tortoises (Centrochelys sulcatabecame unwell after ingestion of wild garlic (Allium ursinum, also known as ramson). The reptiles had haematological findings similar to those seen in other species but Heinz bodies were not a consistent finding. Two of the tortoises died.

Feeding of Allium species should be avoided in companion animals and exotic species.