HPAI: What You Need to Know About Dairy Cattle and Poultry

The highly pathogenic avian influenza (HPAI) virus affects several animal species, including migratory birds and domestic poultry. It has also been isolated from a variety of non-agricultural mammals, with the red fox, house mouse, and domestic cats being the most commonly affected species (USDA, 2025). In 2024, HPAI was first identified in dairy cattle, where it has continued to spread from farm to farm; at the time of this writing, 66 new cases have been confirmed within the past 30 days (USDA 2024). This new agricultural threat of HPAI has prompted producers to enhance their biosecurity and disinfection measures.

Below, we present information about HPAI and tips to safeguard your animals and business.

Virus Basics

• Animals infected with HPAI shed the virus in mucus, saliva, and manure. Infected dairy cattle shed high numbers of HPAI virus in raw milk.
  • Pasteurization of milk inactivates the HPAI virus.
• The virus can be stable in organic matter such as manure.
• HPAI is susceptible to most disinfectants and detergents once the organic matter (manure) is removed.
• Cleaning boots and farm equipment to remove manure before disinfecting is essential!
• For dairy cattle, cases are documented in herds that regularly transport cattle between sites, and in herds that do not regularly transport cattle.
• HPAI may spread from farm to farm on people and their clothing, footwear, or vehicles.
• Fomites such as manured footwear and tires, as well as infected cattle can spread the disease.
• A few cases of HPAI have been documented in dairy and poultry farmers who were in extensive contact with sick animals and/or their secretions.
• The CDC is recommending that poultry and dairy farmers use protective eyewear, dedicated coveralls, and disposable gloves.

Why is HPAI Concerning?

Migratory birds spread the HPAI virus to a new region by leaving behind manure loaded with the virus. The virus can be passed to poultry when they interact with wild birds, their manure, or items contaminated with manure. In poultry, HPAI can cause severe clinical signs, including respiratory distress and sudden unexplained death. Additionally, affected birds must be depopulated according to USDA guidelines.

When dairy cattle are infected with HPAI, their symptoms are not as severe as those seen in poultry, but they can still significantly impact production and profitability. Affected herds show decreased feed intake and milk production, with about 10% of cows showing severe signs. These cows show generalized signs of illness such as lethargy and fever, often produce thickened, abnormal milk, and may have dry, tacky manure. Although the disease is less severe in dairy cattle, poultry exposed to virus originating from dairy cattle still experience severe disease.

Biosecurity on Poultry and Dairy Farms

• All visiting farm service personnel should wear cleaned and disinfected boots and clothing on each farm. This may include disposable boot covers or footwear and/or clothing provided by each farm.
• Separation is key-use different workers for poultry and dairy. If workers are crossing into both areas, then dedicated footwear and clothing is required for each species.
• If employees or service people must move between dairy and poultry operations within their workday, they should visit poultry operations prior to visiting dairy operations.
• The tires of all vehicles entering agricultural animal facilities must be disinfected
• When possible, discourage the presence of migratory birds
• When possible, quarantine cattle transported from other sites

Report Suspected HPAI Signs

Producers should monitor their poultry and dairy cattle for clinical signs of disease. If they are present, contact the Pennsylvania Department of Agriculture at 717-772-2852.

Prevent HPAI: Keep Your Dairy Herd Separated from Your Flock!

Separation between dairy cattle and poultry and strong biosecurity practices are key to reducing the risk of passing the virus between species. Dairy workers should avoid poultry. If this is not possible, a Danish entry system should be implemented, which is described in the next section.

Adhere to these Best Practices:

• Clean and disinfect boots and equipment that must travel between the herd and the flock.
• Require your milkers to wear gloves. If there are hospital cows, isolate them from the rest of the herd and milk this group last.

Danish Entry System

Create a physical boundary between the herd and flock with footwear and coveralls dedicated to each side (see figures).

1. Enter from either the dairy or the poultry side of the farm, remove boots and coveralls, and store them on a cabinet assigned to that animal type. Sanitize hands.
2. Step over in clean socks to the other side of the farm. Wear a dedicated coverall and a clean pair of boots. Enter the other side of the operation.