menadione

Synthetic Vitamin K3 is known to damage liver cells and cause hemolytic anemia. AAFCO no longer recommends it in pet food, but some manufacturers still add it.

Other common names: menadione sodium bisulfite, menadione sodium bisulfite complex, menadione dimethylpyrimidinol bisulfite, vitamin K3, synthetic vitamin K, 合成維生素K3, メナジオン

Sources: ASPCA Animal Poison Control Center, FDA Center for Veterinary Medicine, veterinary literature. For reference only, not medical advice. If poisoning is suspected, seek veterinary care immediately.