The Detroit Zoo said Mike, a 13-year-old grizzly bear, passed away on Wednesday after months of health complications.
According to the zoo, Mike and his brothers, Boo and Thor, were rescued in 2011 after being orphaned in the Alaskan wild.
They later moved to the Detroit Zoo and grew up together, forming an incredible bond.
Zoo officials said that Mike began exhibiting symptoms of discomfort and having a lower appetite earlier this year, and then he became unable to rise from a lying posture.
They implemented intensive care and monitoring and consulted vet neurologists to initiate several treatments, but there were no improvements.
"Mike’s health continued to decline in his final days," the zoo said.
They said they exhausted all options before deciding to humanely euthanize him.
After exhausting all options and continuing to see a decline in his quality of life, the team made the difficult decision to humanely euthanize him.
"These decisions are always hard, but we take comfort in knowing that Mike was loved and provided with the highest level of care during his lifetime. The veterinary team is working to understand the underlying causes behind Mike’s condition, and a necropsy is scheduled for today; we expect to see the results in the coming weeks," officials sayd.
