COLUMBUS, Ohio (WCMH) — One of the four original bonobos of the Columbus Zoo and Aquarium’s bonobo program died this month.

Lady, a 40-year-old bonobo, was humanely euthanized this month after her health worsened, the Columbus Zoo announced in a Facebook post on Monday. Born in the wild in 1982, Lady came to the zoo in 1990 from the Limburgse Zoo in Belgium.

She gave birth to twin boys in 1995, a daughter in 1996 named Tamia, a second daughter in 2002 named Jo-T and another son in 2015 named Max II.

During a routine examination in 2017, it was discovered Lady was suffering from a serious medical condition known as an aortic dissection. The zoo said Lady continued to be monitored closely by the zookeepers and animal staff, and was trained to receive blood pressure measurements.

Recently, staff noticed Lady was more subdued than normal and not interacting with the other bonobos, according to the Columbus Zoo. An examination on Nov. 9 found her condition had worsened, and she had developed additional heart disease. After serious complications during recovery, the zoo decided to humanely euthanize Lady.

Lady’s care team said she was very sweet, reserved, had an extremely close relationship with fellow bonobo Susie and was a great ambassador for her species.