A dairy herd in Morrow County has become Oregon's first confirmed case of bird flu in cattle, after routine milk testing flagged the infection on Nov. 6. The U.S. Department of Agriculture confirmed the detection four days later, on Nov. 10, and state officials say the affected cows have been quarantined while they work to keep the virus from spreading further.
How The Infection Was Caught
According to Nonstop Local, the case was first picked up through Oregon's routine statewide milk surveillance program, with the positive results reported by the veterinary diagnostic laboratory at Oregon State University. The USDA's Animal and Plant Health Inspection Service then confirmed the finding in the Oregon herd on Nov. 10, as reported by Capital Press. USDA's National Veterinary Services Laboratories separately confirmed via PCR testing that the strain is highly pathogenic avian influenza H5 clade 2.3.4.4b, per the agency's own announcement.
State veterinarian Ryan Scholz said Oregon's milk surveillance program identified the infection quickly and enabled a rapid response with state and federal partners. Scholz also said monitoring and preparedness efforts have been backed by Oregon's dairy industry and animal health partners since 2024, the same year the virus first turned up in U.S. dairy cattle nationally.
Containment And Worker Monitoring
The affected cows have been placed under quarantine to restrict their movement, and the Oregon Department of Agriculture says additional disease-control measures have been implemented. No other affected dairies in Oregon had been reported at the time of the report, the station's account notes. In most cases, infected dairy cows are expected to recover within a few weeks.
Public health officials are also providing education to farm workers who were or will be exposed to infected animals, and they plan to monitor those workers for symptoms of bird flu, per the same account. Oregon's only previous bird flu case was two years earlier, in livestock belonging to a backyard producer, not a commercial dairy, Capital Press reported.
Is The Milk Supply Safe?
Oregon Department of Agriculture officials say pasteurized milk and dairy products remain safe to consume and that there is no concern about the safety of the commercial milk supply. Pasteurization effectively inactivates the highly pathogenic avian influenza virus, and milk from sick animals is prohibited from entering the commercial supply in the first place.
The U.S. Food and Drug Administration continues to advise against consuming raw, unpasteurized milk, since it does not undergo the heating process that kills viruses and bacteria. The Oregon Department of Agriculture likewise advises against drinking raw milk as part of its ongoing avian influenza guidance for dairy cattle.
A Virus Already Reshaping Dairy Country
Oregon's case lands amid a broader surge across the region and the country. Bird flu has infected 1,232 dairy herds in 22 states since the outbreak began in March 2024, according to Capital Press, with USDA confirming the virus in 50 herds across five states in just the 30 days before that Nov. 10 report. A separate report published April 8, 2025, from CIDRAP put the national total at 1,000 herds since March 2024, a historical count as of that report.
The spread has hit Oregon's neighbors hard. Washington has had all 43 of its cases confirmed since Oct. 8, Capital Press reported, while Idaho logged two new cases on Nov. 6 to bring its total to 180, second only to California nationally. Back in December 2024, more than 700 herds across 16 states had tested positive, according to OPB, which also reported that Oregon had announced weekly milk testing at every commercial dairy in the state that same month, even though no cattle case had yet surfaced there at the time.
