Bears found with neurological disorders stump researchers


In 2019, a young bear at Northstar California was found fearlessly approaching visitors, acting very “dog-like” and even stepped on the snowboard and curiously sniffed the snowboarder who was filming it on social media.

The bear, who had a prominent head tilt, was very friendly towards people and after being picked up by California Department of Fish and Wildlife, was sent in for CT scans and treated for neurological abnormalities.

The bear’s name, Benji, now resides at the San Diego Humane Society’s Ramona Campus, but other bears around the state have been found with similar abnormalities.

Ann Bryant, of the Bear League, says that about five years ago she found a few bears with similar abnormal characteristics to Benji. She remembers one bear that walked right up to a construction site and was approaching workers being curiously friendly, like a dog would and was strangely almost afraid of food. This bear also had a prominent head tilt and vacant stare, and was just not all there said Bryant.

One female bear that was taken in by CDFW was covered in ticks, undersized, severely underweight, had tremors and head tilt. The bear was euthanized and with post-mortem examination underway, preliminary results have shown encephalitis which is swelling of the brain. Another bear from Humboldt County with symptoms was euthanized and confirmed to have encephalitis as well.

A young black bear showing neurological abnormalities, undergoes a CT scan at UC Davis in 2019. <em id="emphasis-2ab8f6663d69ed588b93ae290c3dcc56">Provided / CDFW / Kirsten Macintyre. </em>

When these bears are found they usually are too young to be on their own, have a pronounced head tilt, tremors, exude “dog-like” personalities, are overly-friendly, malnourished and seem not physically or mentally right. The Nevada Department of Wildlife first encountered this phenomenon in 2014 and alerted wildlife colleagues.

“What brought this current condition to light is a pattern,” said Jamie Sherman, a veterinarian at UC Davis’ One Health Institute who has studied black bear diseases.

This pattern is prompting the next steps of research and she says that encephalitis is causing the neurological abnormalities, but the root cause is still unknown.

“The more we investigate, the more confounding it becomes,” said CDFW public information officer Peter Tira. “This presents multiple challenges, we are very concerned.”

Tira said that findings have not been confined to a specific geographic region either.

During CDFW’s early research they found five new unidentified viruses, but don’t know the what or if there is a relationship to them and this condition.

CDFW and Bryant have dealt with several bears exuding similar abnormalities which have turned out to be encephalitis. Encephalitis can only be accurately determined with a necropsy after the bear has been euthanized, but bears with encephalitis are unable to live in the wild without veterinarian assistance.

“They have this vacant, glazed over look,” she said.

Bryant has hands-on worked with five of these bears with this condition.

“My concern is bears are going to be killed,” she said.

This time of year, yearlings are coming out of hibernation. These yearlings are also very friendly and approach people as they cope with separating from their mothers.

“That behavior is normal for yearlings and dispersing juveniles,” she said.

Bryant said those with a trained eye can know the difference from a friendly yearling and a bear with encephalitis. She said they have already been getting calls the last 25 years for normal, healthy yearlings who are naturally friendly.

While research is still being conducted, Bryant theorizes that this disease could be from ticks.

Bryant does not want the community to be alarmed and says that this disease is still pretty rare. Lake Tahoe Wildlife Care is aware of the disease, but have not treated any at their facility.

Denise Upton, Animal Care Director at LTWC says that the general public might not know what to look for because habitualized bears and bears that have been hit by cars can also have similar symptoms.

If you see a bear behaving oddly, call Bear League 530-525-7297 or LTWC at 530-577-2273.

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