According to zoo officials, Gus had exhibited signs of depression since the death of his last partner, Ida, in 2011. In the summer of 2013 he had poor appetite and difficulty chewing and swallowing food. He was placed under anesthesia by zoo veterinarians to determine the cause of his problem; the veterinarians discovered a large, inoperable tumor in the region of his thyroid and decided to euthanize him.[1] At age 27, Gus had far exceeded the life expectancy of polar bears in captivity, which averages 20.7 years.[2]