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Highly Pathogenic Avian Influenza in Dairy Cattle


dairy cows eating through some railing.

Updated May 7, 2024

The latest information (subject to change)

  • The U.S. Department of Agriculture (USDA) has confirmed highly pathogenic avian influenza (HPAI) in dairy cattle in New Mexico, Texas, Kansas, Michigan, Idaho, Ohio, North Carolina and South Dakota and Colorado. This was confirmed through the testing of clinical samples from sick cattle. 
  • Farms have also reported finding deceased wild birds on their properties, and additional testing is being conducted to address this. 
  • Mechanical transmission is under investigation, as well as transmission from birds. 
  • Detections of avian influenza in birds, including chickens, are common in U.S. in the spring and fall due to wild birds spreading the virus as they migrate to and from their seasonal homes. While it is uncommon for HPAI to affect dairy cows, APHIS has been tracking detections of HPAI in mammals in the U.S. for many years, leading dairy farmers and veterinarians to prepare for the eventual illness. 
  • For the dairies whose herds are exhibiting symptoms, on average about 10% of each affected herd appears to be impacted, with little to no associated mortality reported among the animals. 
  • Milk loss resulting from symptomatic cattle to date is too limited to have a major impact on supply and there should be no impact on the price of milk or other dairy products. 
  • According to dairy farms and veterinarians reporting on affected herds, most affected cows recover with two to three weeks. 
  • Veterinarians in New Mexico are being urged to check with other states on receiving requirements of all cattle prior to shipment.
  • Be sure to check out USDA APHIS’ webpage about HPAI Detections in Livestock. This webpage is updated regularly. 
  • The New Mexico Department of Agriculture and the New Mexico Livestock Board issued a joint  news release regarding the  Federal Order issued April 24 by USDA’s Animal and Plant Health Inspection Service (APHIS). APHIS has issued this Federal Order as part of continued efforts to prevent the spread of HPAI. Be sure to also check out these  guidelines for state animal health officials, accredited veterinarians and producers, as well as  guidelines for workers.

Food supply safety

  • USDA confirmed that dairy products remain safe to consume. Pasteurization (high heat treatment) kills harmful microbes and pathogens in milk, including the influenza virus. 
  • Routine testing and well-established protocols for New Mexico dairies will continue to ensure that only safe milk enters the food supply. In keeping with the federal Grade “A” Pasteurized Milk Ordinance (PMO), milk from sick cows must be collected separately and is not allowed to enter the food supply chain. This means affected dairy cows are segregated, as is normal practice with any animal health concern, and their milk does not enter the food supply. 
  • Pasteurization is a process that kills harmful bacteria and pathogens, including viruses, by heating milk to a specific temperature for a set period of time. Pasteurization continues to be one of the most effective tools we have to inactivate bacteria and viruses in milk. Because milk in interstate commerce is required to be pasteurized, we do not have safety concerns about the pasteurized milk currently in the market.  
  • Dairies are required to send only milk from healthy animals into processing for human consumption; milk from impacted animals is being diverted or destroyed so that it does not enter the food supply. 
  • New Mexico consumers can remain confident in the safety and quality of dairy in the state. 
  • Retail raw milk producing farms have been notified and no symptoms are currently present. Agencies are working with the raw milk industry to increase surveillance for sick cattle and utilize appropriate biosecurity measures.
  • For the latest information on the ongoing work to ensure continued effectiveness of the federal-state milk safety system, be sure to check out  updates on HPAI from the Food and Drug Administration (FDA).

​​​​​​​ Multi-agency collaborations to ensure biosecurity

  • As information related to an illness affecting dairy cows in several states began to circulate over the past two weeks, USDA’s Animal and Plant Health Inspection Service (APHIS) worked with state veterinarian authorities as well as federal partners such as FDA to swiftly identify and respond to detections and mitigate the virus’ impact on New Mexico dairy production.
  • Dairy farmers have implemented enhanced biosecurity protocols on their farms, limiting the amount of traffic into and out of their properties and restricting visits to employees and essential personnel. 
  • The National Dairy FARM Program (NDFP) offers several valuable biosecurity resources providing dairy farmers with tools to keep cattle and dairy businesses safe. These resources include: 
  • HPAI requires birds as the carrier. Most people will not have direct and prolonged contact with infected birds, especially on a dairy farm. Initial testing by the National Veterinary Services Laboratories has not found changes to the virus that would make it more transmissible to humans, which would indicate that the current risk to the public remains low.

What to do if you notice symptoms on your farm

  • Federal and state agencies are moving quickly to conduct additional testing for HPAI, as well as viral genome sequencing, so that we can better understand the situation, including characterization of the HPAI strain or strains associated with these detections.
    • Accredited veterinarians who submit samples upon the State Veterinarian’s direction and approval are eligible to have the samples tested at no cost as part of the response. 
  • Dairy producers with affected cows are reporting rapid onset illness in herds, specifically among older, lactating cows. Clinical signs include:
    • Decreased herd level milk production;
    • Acute sudden drop in production;
    • Decrease in feed consumption; 
    • Abnormal feces and some fever; 
    • Older cows may be more likely to be severely impacted than younger cows
  • Producers who believe dairy cattle within their herd are showing the clinical signs described above should report these signs immediately to the New Mexico State Veterinarian at the New Mexico Livestock Board at 505-841-6161.

What to know for the days ahead

This is a rapidly evolving situation, and USDA and federal and state partners will continue to share additional updates as soon as information becomes available.

If you believe you have any dairy cattle HPAI incidents to report, or have observed suspicious deaths of wildlife, please complete the form below. All reports will be thoroughly investigated, as necessary, by state and federal authorities.