Veterinarians said Rio, who had exceeded the known median life expectancy of river otters by almost a decade, was experiencing a "progressively deteriorating health and quality of life" in a statement. She was euthanized Tuesday at the age of 21.
The female otter, whose name means "river" came to Shedd in 1992 from Little Rock Zoo in Arkansas. River otters were on the endangered species list in Illinois then.
