DENVER (AP) -- An elderly lion at the Denver Zoo has died while being treated for cancer.
Zookeepers noticed in March that the lion named Rian had grown lethargic. Tests found a large mass in his abdomen and he was euthanized on Wednesday.
The lion was undergoing an experimental treatment based on therapy typically used for domestic cats suffering from lymphoma.
Veterinarians were hoping to gather valuable information about how chemotherapy could help other zoo lions and large cats.