(NEXSTAR) – Three juvenile grizzly bears found disoriented and suffering from neurological issues such as partial blindness tested positive for avian flu, Montana wildlife officials confirmed Tuesday.

The bears were found in poor condition last fall and were euthanized, according to Montana Fish, Wildlife & Parks.

“We suspect these mammals probably get the virus from consuming infected birds,” said FWP Wildlife Veterinarian Jennifer Ramsey in a news release. One was found in Augusta, another in Dupuyer and the third in Kalispell, all located in northern Montana.

They were the first documented cases of the virus in grizzly bears, according to Montana officials. U.S. Department of Agriculture records on bird flu in mammals show that another grizzly bear, living in a zoo, died around the same time as the Montana cases.

Montana wildlife officials didn’t immediately respond to Nexstar’s request for additional information.

Tests last year also confirmed HPAI in a fox and a skunk in Montana, officials said. In other countries, the disease has been documented in animals including pigs, cats, dogs, tigers, and leopards, among others.

The bird flu hit U.S. egg farmers especially hard last year, prompting the slaughter of tens of millions of chickens and driving up the price of eggs in the process.

Highly pathogenic avian influenza (HPAI or H5N1), can be fatal to poultry and has ripped through bird populations in Asia, the Middle East, Europe and Africa since December 2003, according to the Centers for Disease Control and Prevention.

The virus could potentially spread to people and cause serious disease, according to the CDC, although the risk is considered to be very low. Wildlife officials urge people to take precautions when handling game birds; sick or dead birds; or other mammals.

“Even if an animal is not suspected to have died from a contagious disease, gloves should always be worn if a dead animal must be handled for disposal,” Montana FWP said.