KNOXVILLE, Tenn. (WATE) — Another bear cub at Appalachian Bear Rescue has died due to an illness related to a bacteria, marking the third to pass away as a result of the illness.

Appalachian Bear Rescue reported that Thumper’s breathing became labored on Saturday afternoon. Thumper was rescued from Elizabethton in April after many residents observed him attempting to climb a tree alone near a parking lot and roadway. He was ten weeks old and only four pounds when he was first rescued.

A video was initially sent to the University of Tennessee College of Veterinary Medicine (UTCVM) for review after one of the curators noticed Thumper’s condition. Two veterinarians came to ABR and examined the bear.

“Thumper’s prognosis isn’t good; the curators are doing everything they can to keep him eating and comfortable. Thumper is back on oral antibiotics but decided he doesn’t like sardines. Curator Cole supplied him with a variety of foods to see which one appealed the most: cubby bearysauce seems to be in the lead,” wrote ABR on Sunday.

The cause of the illness that killed Thumper, Flapjack and Burrito, and made four other cubs sick, may have been found. Veterinarians from UTCVM believe that a specific strain of bacteria found in the gallinaceous birds such as domesticated chickens and turkeys could be responsible.

The two other sick bear cubs, Martha Washington and her sister, Betsy Ross, are doing well according to ABR. The curators are monitoring their breathing.