The National Zoo’s oldest sloth bear, Merlin (left), pictured here in 2008 with female sloth bear, Khali, passed away this morning. Photo Credit: Mehgan Murphy/Smithsonian’s National Zoo.

Another sad death to report at the Smithsonian’s National Zoo. Merlin, the Zoo’s oldest male sloth bear, died this morning after a 48-hour illness, according to a news release. He was 28 years old.

On Monday morning, Nov. 2, he underwent a routine physical examination. Although the examination went well, his anesthetic recovery was prolonged, and he had not returned to normal by the afternoon. While under observation, veterinarians noticed that he had vomited some blood-tinged fluid.

Due to concerns with this prolonged recovery, the vomiting and his previous medical history of a gastric volvulus (“twisted stomach”) in 1994, he underwent additional evaluation and diagnostics at the National Zoo’s hospital later the same day. Based on the results of his blood work, ultrasound and radiographs, the animal care team determined he required surgery, during which they corrected a partially twisted spleen. Following the procedure, Merlin showed signs of increased wakefulness, but never fully recovered. Sequential blood work analysis suggested additional metabolic compromise, including possible circulatory shock and renal failure.

The bear was attended by staff who remained on 24-hour watch and provided intensive care continuously for two days, until he passed away this morning. A necropsy will be performed later today, but results will not be available for several weeks.

Merlin was born at the National Zoo in 1981, and sired a total of seven cubs during his life. The Zoo has two female sloth bears currently on exhibit, Hana and Khali.

Late last week, the Zoo announced the deaths of two rare scimitar-horned oryx, both of whom died shortly after having been anesthetized for separate, routine medical exams.