One of the oldest lions in the US dies at the National Zoo

WASHINGTON (CNN) – The Smithsonian National Zoo in Washington said goodbye to a beloved resident Thursday.

Veterinarians at the zoo euthanized Shera, an African lion.

Though the loss saddened staffs, Shera lived a long life for a lion at 21 years.

The average lifespan of an African lion in captivity is 17 years. Twenty-one in lion years is equivalent to 100 for humans.

Veterinarians decided Shera’s arthritis and other medical issues were beginning to hamper her enjoyment of life.

Shera mothered eight cubs during her time at the zoo. Two of them are still at the National Zoo.

Shera was one of the two oldest lions in U.S. zoos.