NEW YORK (CBSNewYork/AP)The Bronx Zoo announced that it euthanized an Asian elephant after an illness.

Maxine was 48 years old. She had a “progressive illness,” suffered “neurologic deterioration and generalized muscle weakness,” the Bronx Zoo said in a statement.

The decision was made to euthanize her after she was no longer able to eat.

maxine Maxine, 48 Year Old Elephant, Euthanized At Bronx Zoo After Illness

Maxine the Asian Elephant (credit: WCS/Julie Larsen Maher)

“Everyone at the Bronx Zoo is deeply saddened by the loss of Maxine. Some of us have known and worked with her for over 40 years as she came to the zoo in 1973. We have great memories of Maxine; she was a wonderful animal with a great personality. She was loved by those who cared for her each day as well as the millions of visitors she inspired in over four decades at the Bronx Zoo. This was a really difficult day for all of us at the zoo.” said Jim Breheny, Director of the Bronx Zoo and EVP of Zoos & Aquarium at the Wildlife Conservation Society.

Maxine’s death leaves the zoo with two remaining elephants: Happy, 47, and Patty, 48.

“After exhausting all options to treat Maxine and since she was no longer able to eat, we made the decision to euthanize her. She died a peaceful death, surrounded by the keepers, curators and veterinarians who had cared for her throughout her life. And afterwards, we gave Patty, who had lived with Max since they both arrived at the Bronx Zoo, the chance to spend time with her and understand what had happened to her friend,” Breheny said.

Zoo officials say they’re monitoring Patty and Happy as they cope with Maxine’s death, and will evaluate the elephant program.

“With the death of Maxine, we will assess our elephant program,” Breheny said. “The plan we develop for our elephants moving forward will be based on our expertise in elephant behavior and husbandry, veterinary evaluation — and, most of all, on an intimate, in-depth understanding of our individual animals and their needs.”

Last month, an animal welfare group brought legal against the zoo, claiming Happy has similar rights to a human being and is being unlawfully imprisoned.

In a legal petition filed in Orleans County, the Nonhuman Rights Project claimed Happy lived mostly alone since her mate was fatally injured in 2002 and should be relocated from the zoo to a larger private sanctuary.

Zoo officials say Happy is content, not isolated and might suffer from a transfer. Breheny said the lawsuit is based on “ludicrous legal arguments and lies.”

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)