Angel, an aging 17-year-old giraffe born and raised at the Maryland Zoo in Baltimore, was euthanized Tuesday, officials said.
Angel long struggled with leg and back pain, which worsened recently, Dr. Ellen Bronson, the zoo's chief veterinarian, said in a statement.
"While we were able to provide her with pain medicine which made her more comfortable, we realized that her quality of life was declining and the decision was made to euthanize her," Bronson said.
She is the fourth older female giraffe to die at the zoo since 2008. Gretchen, 22, died in 2008; Mary, 24, in 2010; Zoe, 16, in 2011. The median life expectancy for giraffes in zoos is 15.8 years.
Despite efforts to treat Angel's pain, Bronson said keepers often found her lying down lately, which was not typical for her.
"Because of the great work the keepers did training Angel to enter the giraffe chute voluntarily, we were able to devise many creative therapies for safely treating her up-close, including ultrasounds and hoof trims, and extending her time with us," Bronson said.
Zoo spokeswoman Jane Ballentine said Angel had been hand-raised by staff, and in her later years, was a leader of the herd, helping her younger cohorts become acclimated to the feeding station. She was not shy, and would freely snag a branch of acacia from a visitor's hands, Ballentine said.
"It has been wonderful to have her help the three new female giraffe acclimate to their home at the Zoo, and she was also a favorite with guests who were able to feed her at the Giraffe Feeding Station," Mike McClure, the zoo's general curator, said in a statement. "We will all miss her greatly."
Officials euthanized her with a dose of veterinary anesthetic adjusted for her size, Ballentine said.
Angel was the last giraffe to be born at the zoo, which is home to four other giraffes, including three females, 4-year-old Kesi, 2-year-olds Anuli and Juma, and 7-year-old Caesar. As Angel got older, the zoo brought in the other three females in 2013 and hope to breed Caesar and Kesi, Ballentine said.
Angel was a reticulated giraffe, one of nine recognized subspecies of giraffe.