Zoo Atlanta shared Friday that its oldest giraffe has died.

Abu, 16, had a sharp decline in health and had been monitored by veterinary teams in recent days. Given his “poor prognosis and with concern for the impact on his quality of life,” they made the “extremely difficult decision to euthanize him”, Zoo officials said.

“This is a very sad day for Zoo Atlanta. Abu was very special to so many, both within the Zoo team and among our Members and guests,” said Sam Rivera, DVM, Senior Director of Animal Health. “Our Animal Care and Veterinary Teams have worked tirelessly in their efforts to care for Abu, always with his well-being foremost in our minds, and pursued every option available to us in terms of his treatment. We have all appreciated the amazing support of our Zoo Atlanta community, Members and friends for our efforts and for Abu.”

Abu arrived at Zoo Atlanta in 2007, and became a father in 2010 to the first giraffe calf ever born at Zoo Atlanta, the Zoo said in a press release. In 2011, he sired a second offspring, becoming the dominant member of an all-male herd. The two other giraffes at Zoo Atlanta are males Etana and Isooba, both 10 years old.

A necropsy, similar to an autopsy, will be performed, the Zoo said. Pathology results should be available in several weeks.