PORTLAND, Ore. (KOIN) – Two domestic cats in Oregon died in December 2022 from highly pathogenic avian influenza, the bird flu that began spreading rapidly in 2020. 

The virus can pass quickly and easily between birds, but is less common in mammals. 

In Linn County, two barn cats were diagnosed with it. 

According to Dr. Ryan Scholz, a veterinarian with the Oregon Department of Agriculture, the cats lived on a farm with a poultry flock. The birds in the flock had contracted HPAI and were euthanized by ODA about one week before the cats began showing neurologic symptoms. 

Scholz did not provide KOIN 6 News with specific details about the cats’ symptoms, but the National Institute of Health has said animals infected with this particular strain of the bird flu, H5N1, had high fever, panted, showed symptoms of depression, muscle soreness and nervousness. 

“There is no known treatment for HPAI in mammals, although there is very little information known about this strain in mammals,” Scholz said. 

HPAI has the potential to infect both humans and animals. However, Scholz said mammals are not believed to be significant carriers or spreaders of the virus. It is spread much easier through birds. 

He said most bird flu cases diagnosed in mammals have appeared to be “dead-end” infections, meaning they were not spread to other animals beyond the one diagnosed. 

In the case of the cats in Linn County, Scholz said ODA believes they contracted the exact same strain of the virus that had infected the poultry on the farm. 

“HPAI is not believed to pose a significant risk to domestic cats. In the case in Oregon, the cats lived with the infected poultry and had significant direct exposure to the birds,” he said. 

Most wild mammal cases are believed to have been caused by the animals scavenging and eating wild birds that died from the virus, Scholz said. 

According to the U.S. Department of Agriculture, the H5N1 strain of bird flu has been confirmed in other mammals including the American marten, skunks, and a raccoon. 

Across the United States, it has also been diagnosed in mountain lions, foxes, bobcats, black bears, possums, grizzly bears, seals and even a bottlenose dolphin.

Other cases of bird flu have also been found in domestic cats in Nebraska and Wyoming. 

Scholz said there are ways people can protect their backyard flocks from the bird flu, which might also help protect their cats. 

He suggests keeping a pair of shoes that is only used for wearing inside a chicken coop or poultry pen. Shoes worn elsewhere can pick up bird feces that could be infected with the virus and track it into a backyard flock enclosure, infecting the birds inside. 

People should also wash their hands before entering enclosures. 

He recommends bird hunters disinfect their equipment and wear clean clothes, not their hunting clothes, inside their chicken coops. 

The USDA said people should buy birds from reputable sources and should isolate any birds returning from shows for 30 days to watch for signs of illness before placing them in with the rest of the flock. 

Bird owners should also keep their poultry away from wild birds. For example, free-range chickens should not be allowed to venture near ponds or other areas frequented by wild ducks or geese.