DALLAS, April 3 (UPI) -- The only lion at the Dallas Zoo, Boris, has died after exhibiting signs of distress throughout the week, zoo officials said.
X-rays revealed several growths in the chest of the 17-year-old, 415-pound African lion, The Dallas Morning News reported Wednesday.
Zoo staff said they saw a large cancerous mass putting pressure on Boris's internal organs before his Wednesday death. A necropsy reportedly will decide the formal cause for the lion's death.
Zoo staff said they are considering a memorial for the big cat, which spent 11 years at the Dallas Zoo.
"We can never replace Boris, but we have every intention of bringing lions back to the Dallas Zoo in the future, once we have completed our African savanna exhibit," zoo director Gregg Hudson said.