For more than 15 years, Noah's Ark Animal Sanctuary in Locust Grove, Georgia, has been home to an unlikely trio of best friends. Leo the lion, Shere Khan the tiger and Baloo the bear have been together ever since the animals were rescued from a drug baron's home in Atlanta.

Sadly, Leo underwent surgery in mid-August — after several weeks of being severely ill — and veterinarians discovered that more than 80 percent of his liver was full of tumors. Because of the findings, they decided to let the lion go.

"Both Baloo and Shere Khan were able say goodbye to their lion brother, and we will monitor them closely for any signs of stress or depression as they are grieving the loss of a family member as well," the sanctuary posted in a statement on Facebook.

The trio has been inseparable since they arrived at the sanctuary. The friends never fought, according to the sanctuary, but often playful Shere Khan was quite the prankster. In this video, he pounced on Leo, who was minding his own business, playing with a barrel.

baloo, leo and shere khan bear lion and tigerLeo, Baloo and Shere Khan were a hit with visitors to the sanctuary in Georgia. (Photo: Noah's Ark Sanctuary/Facebook)

Leo was also known for being very chatty with his keepers. Here's a video of him "talking" to them:

Goodbye, Leo. You'll be missed.

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.