The northwoods black bear that attacked a pet dog and three men last month near Isabella was deranged by severe brain swelling and had two external abnormalities that suggest the animal possibly was captive at one time.
Minnesota Department of Natural Resources bear research biologist Dave Garshelis said in an exclusive interview Friday that the agency is still investigating the bear's history and is asking the public to call the DNR's information hot line with any tips. Meanwhile, veterinary pathologists at the University of Minnesota continue to probe what caused the bear's encephalitis. Bacterial causes have been ruled out, Garshelis said.
"They characterized the swelling as severe, extensive and subchronic [reoccurring],'' Garshelis said. "It would have significantly influenced the bear's behavior … even for several weeks before the attacks."
Garshelis, based in Grand Rapids, was among the first to examine the bear after it was fatally shot in the face by a DNR conservation officer from Ely and a Lake County deputy sheriff. The officers were on an emergency assignment to stop the bear's rare rampage. The animal's life-threatening attacks occurred in daylight on Dec. 19 outside two residences deep in the woods near McDougal Lake.
Garshelis said pathologists were able to delineate the profound swelling in the animal's brain from the acute injury from the blast. He said the case involves two other mysteries: a swath of missing hair all around the bear's neck and damaged rear claws.
On the neck, scar tissue was built up and hair follicles were missing in a complete ring ranging from 1 to 2 inches wide, Garshelis said. He said the distinct injury makes him think the bear had a snare or collar around its neck at one time.
But unlike research collars that sometimes cause temporary hair loss in certain patches, the missing hair on the diseased bear was permanent and fully circular, he said. "It was something around the bear's neck that either fell off or was taken off and the hair didn't regrow,'' Garshelis said. "That part of it is a little difficult to understand."
With bacteria ruled out as a cause for the bear's brain inflammation, officials don't see how the neck trauma could be related to the encephalitis. Garshelis said pathologists are checking possible viral or fungal causes for the swelling.