Gus

Gus was a polar bear in Central Park Zoo who was described as “bipolar”, “neurotic”, and “depressed.” He swam obsessively 12 hours a day and was the first zoo animal to be given Prozac. He eventually stopped eating and when he was placed under anesthesia to determine the cause of his problems, he was found to have an inoperable thyroid tumor. So he was euthanized in 2011.