The Columbus Zoo and Aquarium announced Toni, a western lowland gorilla, was humanely euthanized Sunday.
The zoo says the decision was made as her health had recently and significantly declined with her advanced age and health complications.
Toni, who was 48, exceeded the median life expectancy of lowland gorillas by almost 10 years.
In early November, the zoo says Toni showed signs of lethargy and not feeling well ahead of a regularly scheduled cardiac exam.
She was diagnosed with significant cardiac issues and was put on a treatment plan.
The zoo says Toni's care team noticed changes in her behavior and she was experiencing mild seizures within the last week.
After more tests, a decision was made to euthanize Toni.
Toni was born on Dec. 28, 1971 to mother Colo and father Bongo at the Columbus Zoo. She was the last surviving offspring of Colo.
