Two dairy herds have tested positive for bird flu in Washington dairy cattle, the first confirmed infections in the state’s livestock since the multiyear outbreak began, according to federal animal health officials.
The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service confirmed the detections on Oct. 8 after animals in both herds showed illness consistent with highly pathogenic avian influenza.
Federal laboratories identified an H5 subtype of highly pathogenic avian influenza using polymerase chain reaction testing. Officials said additional sequencing is underway to better characterize the virus.
Both herds had previously returned negative results under the National Milk Testing Strategy, a federal surveillance program created to detect the virus in dairy cattle and limit spread.
The detections make Washington the 19th state to report infections in dairy cows since March 2024. Although the pace of new cases has slowed in 2026, the findings indicate the virus remains a continuing risk for dairy operations, according to officials.
Bird flu in Washington dairy cattle raises new concerns
State and federal teams are conducting further testing, on-farm investigations and epidemiological tracing to determine how the virus reached the affected herds and whether additional cattle were exposed.
Biosecurity remains critical for dairy producers
The Washington findings have renewed attention on farm biosecurity as producers manage disease risks more than two years into the outbreak.
USDA officials said the detections do not alter the current eradication strategy, which focuses on surveillance, early detection and measures that reduce transmission between farms.
Recommended precautions for dairies include limiting nonessential visitors, monitoring animal movements, cleaning and disinfecting shared equipment, and reducing opportunities for contact between cattle and potentially infected wildlife.
Research presented at the 2025 MILK Business Conference and reported by Dairy Herd Management found that 68 percent of dairies with at least 250 cows had biosecurity plans in place, while 34 percent said they did not regularly review those plans.
The findings also noted gaps such as more than 20 percent of dairies not securing barn access and 38 percent not restricting entry to feed-storage areas.
The latest detections highlight the need to consistently implement biosecurity measures rather than rely only on written plans, officials said. USDA continues to provide financial assistance to help producers strengthen prevention efforts and defray certain costs related to avian influenza.
What dairy producers should watch for
Highly pathogenic avian influenza can produce a range of symptoms in dairy cattle, some of which resemble other common conditions.
Signs to monitor include:
- Sudden declines in milk production
- Reduced appetite and feed intake
- Thickened, discolored or colostrum-like milk
- Changes in manure consistency
- Fever, dehydration or unusual lethargy
Producers observing unusual signs, especially across multiple animals, should contact a veterinarian promptly to discuss testing and reporting. USDA also recommends reporting unusual illnesses or deaths in livestock and wildlife to state animal health authorities.
Despite the detections, federal officials emphasized that the commercial milk supply remains safe. The Food and Drug Administration states pasteurization inactivates the avian influenza virus, protecting consumers who purchase commercially pasteurized dairy products.
Milk from affected animals must be diverted from processing or destroyed. Only milk from healthy cows can enter the food supply.
The Centers for Disease Control and Prevention continues to assess the risk to the general public as low. However, individuals with higher exposure such as dairy workers and veterinarians should follow recommended protective measures.
The Washington cases come as livestock producers track other emerging disease concerns. In late September, Wisconsin officials confirmed epizootic hemorrhagic disease in dairy cattle in Waukesha County, the first confirmed cattle detection there since 2013. While unrelated and spread through different pathways, both developments underscore the importance of close herd monitoring and prompt investigation of unusual symptoms.
The Washington cases come as livestock producers track other emerging disease concerns. In late September, Wisconsin officials confirmed epizootic hemorrhagic disease in dairy cattle in Waukesha County, the first confirmed cattle detection there since 2013. While unrelated and spread through different pathways, both developments underscore the importance of close herd monitoring and prompt investigation of unusual symptoms.
The Washington cases come as livestock producers track other emerging disease concerns. In late September, Wisconsin officials confirmed epizootic hemorrhagic disease in dairy cattle in Waukesha County, the first confirmed cattle detection there since 2013. While unrelated and spread through different pathways, both developments underscore the importance of close herd monitoring and prompt investigation of unusual symptoms.