Arsenic (As) is well known as a poison. Once a common ingredient in rat and roach bait, arsenic poisoning was mainly a concern for dogs and cats that consumed the toxic bait or afflicted rodents, and cattle whose curiosity likewise led to their ingestion of the hazardous material. Arsenic poisoning in animals is characterized by trembling, abdominal pain, seizures, difficulty with coordinated motion, and paralysis of the hind limbs. When absorbed, arsenic inactivates up to 200 enzymes and binds to essential proteins, wreaking havoc on proper cell function. Arsenite, formed through the reduction of an arsenic compound (described above), binds to the tripeptide antioxidant, glutathione, following the reaction below. Glutathione protects cells from oxidative destruction due to attack by harmful free radicals, and its inhibition facilitates cell death and further DNA and protein damage.