The two Asian elephants, Cha Cha and Cookie, had spent decades at the zoo's Wild Animal Park -- now called the Safari Park -- before being moved to the zoo in 2009, the Los Angeles Times reported Friday.
Cha Cha, estimated to be 43 years old, was euthanized Wednesday, and Cookie, thought to be around 56, was euthanized Friday, the newspaper said.
Elephant keepers performed an emergency procedure on Cha Cha on Christmas Day after noting she was having trouble eating and drinking, removing a large mass of food blocking her esophagus.
But within two days, she began to rapidly decline, they said.
Cookie had been in distress for months with a variety of geriatric issues and had begun to drag her back legs, zoo officials said.