H5N1 in backyard poultry: What you need to know

With an increasing incidence of highly pathogenic avian influenza (HPAI) H5N1, it’s important to be prepared to answer questions if you get a call about a sick chicken or other backyard poultry. It is also essential to know how to keep your staff and other patients safe if a suspect case enters your clinic. Here is what you need to know to help your clients navigate this evolving threat.

What is the current situation with HPAI H5N1?

The current outbreak of H5N1 in the U.S., which began in 2021 when the virus was introduced through migratory birds, has affected poultry, domestic cats, dairy cattle, several species of wildlife, swine, and a small number of people (see table below showing reported cases). H5N1 HPAI has been detected in commercial and backyard or hobbyist flocks across all 50 states, causing significant losses.

What is HPAI H5N1 and its significance in backyard chickens?

H5N1 is a subtype of avian influenza virus (or “bird flu”) that primarily affects birds but has the potential to infect other wild and domestic animals (e.g., pigs, horses, cows, cats, and dogs) and sometimes people. Backyard chicken flocks, along with captive pet birds that have outdoor access, are vulnerable. This subtype (along with other H5 and H7 influenzas) is also referred to as highly pathogenic avian influenza (HPAI) because of its ability to cause severe disease and death in poultry. HPAI strains can lead to death in 75-100% of chickens and can pose significant risks to other animals, as well as people.

What are the clinical signs of HPAI in backyard poultry?

Clinical signs are variable and can include all or a combination of one or more of the following:

• Sudden death with no prior signs of illness
• Lethargy, anorexia, and ruffled feathers
• Respiratory signs (coughing, sneezing, nasal discharge, dyspnea, and cyanosis or bluish discoloration of the head, eyelids, comb, wattles, or legs)
• Neurological signs (tremors, head tilting or twisting of the neck (torticollis), paralysis)
• Drop in egg production or misshapen, soft-shelled eggs
• Diarrhea

How is H5N1 transmitted?

H5N1 can be transmitted in backyard chickens via:

• Direct contact with infected birds
• Indirect contact via contaminated water, feed, equipment, and shoes/clothing
• Inhalation via airborne viral particles

Wild birds can spread the virus to backyard flocks through their droppings and contaminated feed or water. Although rare, transmission from birds to mammals—including domestic cats and dogs—has been documented. Veterinarians should recognize potential risks, particularly in households with multiple pet species. To reduce risk, pets should be kept away from chicken areas and not be fed raw or undercooked poultry products.

Transmission of the virus from chickens to people is rare but has also been reported.

Should my clients be concerned about eating eggs from their backyard chickens right now?

According to the FDA, the risk of contracting H5N1 from eggs is low if they are thoroughly cooked to the proper temperature of 165°F and if cross-contamination between raw and cooked food is prevented. Always cook poultry and poultry products, including eggs, thoroughly before consuming and advise against eating eggs from affected flocks. No human bird flu infections have been reported in the U.S. from eating properly handled and cooked poultry or poultry products.

What do I do if I suspect HPAI in a backyard chicken or flock? 

If a client calls you and one or more of their chickens is exhibiting signs of HPAI (noted above), you want to act quickly to protect people and other pets in the household.

Contact authorities to report the sick/dead birds and for specific guidance on testing and disease control in your area.

• Contact your state animal health official or state/federal agricultural agency (USDA APHIS at 1-866-536-7593) and state public health veterinarian to report the sick/dead birds.
• Consult your state animal health official to identify which test to use in your area. There are 60 diagnostic laboratories approved for testing for influenza A viruses in avian species.
• Consult your state animal health official on guidance for disease control

Instruct clients on the following measures to prevent spread:

• Isolate sick birds immediately in a manner that does not involve direct handling without wearing personal protective equipment (PPE).
• Ensure no one moves the birds, eggs, or materials off the property.
• If handled sick/dead birds or entered an area with potentially contaminated debris or materials, change clothes and shoes before entering the home.
• Ensure pet cats and dogs do not have access to the area.
• Dispose of waste according to guidance from the state animal health official.

Ensure clients avoid direct handling without PPE for their own safety:

1. • No direct handling of sick and dead birds, their feces or litter, and surfaces and water sources that may be contaminated without wearing PPE.
   • For PPE, follow the Centers for Disease Control and Prevention on PPE for backyard flocks (gloves, N95 masks, and protective clothing) to minimize potential exposure to the virus.

Do not attempt treatment and follow official instructions – there is no effective treatment for HPAI H5N1 in poultry.

• Recovery of poultry from HPAI is very rare.
• Infected poultry are typically euthanized.
• Follow official guidance from the state veterinarian or state/federal agricultural agency regarding isolation, culling, and disposal of affected birds.

Is there a vaccine for H5N1 for use in backyard chickens?

No. There is a killed version of an H5N2 variant that was designed to be effective against circulating variants of the H5N1 virus, but the USDA has not approved it for use in domestic poultry in the U.S. Currently, there are special regulations that prohibit poultry vaccination against avian influenza viruses in the U.S. due to concerns regarding impacts on trade.

What guidance can I provide to my clients on how to protect their backyard flocks during the H5N1 outbreak?

If clients are interested in starting a flock, please advise them of the public health and animal health risks of doing so during this outbreak. According to Dr. Rodrigo Gallardo, DVM, PhD, a Poultry Veterinarian and Avian Virologist at the University of California, Davis, there are a number of important biosecurity measures that families with backyard flocks should apply to protect their flocks during the outbreak:

Keep visitors to a minimum

• Anyone visiting the birds will need to wash their hands thoroughly with soap and water and change clothes and footwear.
• Limit visitors who have been in contact with other birds or any animal potentially exposed to H5N1.

 Practice good hygiene/sanitation

• Wash hands with soap and water before and after working with the flock.
  • An alcohol-based hand sanitizer can be used when hand washing is not available, but only if you can first remove any manure, dirt, or feathers as organic material can limit effectiveness.
• Have dedicated clothing (e.g., coveralls) and footwear (e.g., slip-on boots) that are worn only when attending to the flock. Keep designated clean footwear/boots near the door of the coop/poultry enclosure. A footbath can be added as extra protection. If using a footbath, be sure to remove all droppings, mud, or debris from boots and shoes using a long-handled scrub brush before stepping into the disinfectant footbath and always keep it clean.
• Clean and disinfect equipment, tools, and surfaces regularly.
• Avoid sharing poultry equipment or egg cartons with other flock owners to prevent cross-contamination.

Limit or halt movements of birds to sales and shows

• Halt or limit movement of birds as the virus can be spread from one flock to another.
• If attending any poultry sales or shows, use dedicated clothes and footwear and ensure clean hands when handling birds and separate any exhibition birds from the flock for at least 30 days.
• Limit obtaining new birds. If doing so, quarantine new birds for at least 30 days prior to introduction to an existing flock.

Limit exposure to wild birds and other wild and domestic animals

• Cover or enclose areas for poultry. Use an enclosed shelter and fence outdoor areas. Smaller mesh hardware cloth can be used to minimize contact with wild birds and rodents. Keep the area clean of wild bird droppings and feathers.
• Keep feeders and waterers clean and inaccessible to wild birds. Clean up spilled feed promptly to avoid attracting wild birds and rodents. Also, reduce natural food sources (e.g., fallen fruit) and cover compost and food waste.
• Use deterrents (e.g., predator decoys) to keep wildlife away from areas with backyard chickens.
• Minimize standing water that may attract wild birds and do not allow flocks to visit open water sources where wild ducks and other wild birds gather.
• For waterfowl hunters, avoid poultry contact with hunting equipment, clothing, footwear, vehicle, and dogs to prevent spread from contaminated wetland habitats.
• Keep pet cats and dogs away from poultry keeping areas.

Gallardo stressed the importance of “reminding poultry keepers of the need for dedicated clothing and footwear for biosecurity in backyard flocks and educating them on common risk factors for introducing H5N1 to flocks, such as trips to the feed store.” H5N1 and other poultry pathogens can be carried back to your flock on clothing and footwear when visiting places like feed stores and neighbors’ homes with backyard flocks. He said that “the virus can remain viable in fecal matter in the environment for up to 1 week, so it’s crucial to change into clean footwear and clothing before tending to your flock to prevent accidental introduction of the virus.”

USDA’s Defend Your Flock resources offer free tools and resources to help individuals handling backyard chickens follow proper biosecurity practices including a biosecurity checklist.

How can I protect myself and staff when working with suspect HPAI H5N1 cases in chickens?

Please advise your care team of the clinical signs of HPAI H5N1. Ensure that staff responsible for scheduling are aware not to book in-person appointments for backyard poultry showing signs of HPAI H5N1. Instead, they should promptly notify you, as this is a reportable disease in chickens. Contact your state animal health official or state/federal agricultural agency (USDA APHIS at 1-866-536-7593) and state public health veterinarian for guidance on testing and disease control. This is a reportable disease in chickens–so, regardless of client preferences, the state veterinarian will need to be notified of a possible case to protect other animals and people in the community.

While human infections with H5N1 are rare, they can be severe. Veterinarians and veterinary staff caring for suspect HPAI H5N1 cases in chickens must take precautions:

Review AAHA guidelines on infection control with your staff and make sure you have an effective infection control plan in place.

Contact state veterinarian and state public health veterinarian.

Follow CDC’s guidance on PPE when handling sick or dead birds:

• Disposable or non-disposable fluid-resistant coveralls or gown*, and depending on task(s), add disposable or non-disposable waterproof apron

Preferably, fluid-resistant coveralls should be made of material that passes:

• AATCC 42 ≤ 1 g and AATCC 127 ≥ 50 cm H2O or EN 20811 ≥ 50 cm H2O; or
• ASTM F1670 (13.8 kPa); or
• ISO 16603 ≥ 3.5 kPA
• Properly fit tested NIOSH Approved® particulate respirator (e.g., N95® or greater filtering facepiece respirator, elastomeric half mask respirator with a minimum of N95 filters)
• Properly fitted unvented or indirectly vented safety goggles** or a face shield if there is risk of liquid splashing onto the respirator

Preferably, safety goggles should conform to ANSI Z87.1 that are marked at least Z87 D3

• Rubber boots or rubber boot covers with sealed seams that can be sanitized or disposable boot covers for tasks taking a short amount of time
• Disposable or non-disposable head cover or hair cover
• Disposable or non-disposable gloves

Place the suspected case in an isolation area.

1. Decontaminate any surfaces with quaternary ammonium compounds or other listed virucides by EPA.
2. Staff exposed to H5N1 cases should follow CDC’s guidance to monitor their health for flu-like symptoms for a 10-day period. If symptoms develop, they should seek medical attention and contact their state/local health department immediately for guidance.

How can I stay informed?

Veterinarians are on the frontlines of this response effort. By staying informed on H5N1 HPAI, recognizing clinical signs, and reinforcing biosecurity measures, you can play a vital role in protecting backyard flocks and mitigating risks to other animals and people. The USDA, CDC, and state veterinary offices provide regular updates on outbreaks and biosecurity recommendations.

Key contacts:

• State Animal Health Officials
• State Public Health Veterinarians
• National Animal Health Laboratory Network Laboratories
• USDA APHIS Veterinary Services Offices

Situational Update:

The numbers represent reported cases, not the actual number of affected individuals.

* Information on modes of transmission are suspected or verified based on reported evidence for each species. In general, avian influenza viruses can be transmitted through direct contact, indirect contact (e.g., contaminated surfaces), and inhalation.

**The HPAI virus initially detected in dairy cattle, H5N1 clade 2.3.4.4b genotype B3.13, was the only strain known to infect dairy cattle. However, in early 2025, two spillover events involving a different genotype circulating in migratory birds, D1.1, occurred in dairy cattle in Nevada and Arizona. Ongoing new introductions will complicate efforts to control the virus in dairy cattle, underscoring the importance of robust surveillance and prevention measures.

Where can you go to learn more?

APHIS/USDA Avian Influenza

APHIS/USDA Avian Influenza Detections in Poultry

APHIS/USDA Avian Influenza Detections in Wild Birds

APHIS/USDA Information on Biosecurity for Backyard Flock Owners

APHIS/USDA Protecting Captive Wild Birds From Highly Pathogenic Avian Influenza

CDC Summary of Avian Influenza

CDC H5N1 Informational Videos

CDC Considerations for Veterinarians: Evaluating and Handling of Cats Potentially Exposed to Highly Pathogenic Avian Influenza A(H5N1) Virus

CDC Information for Workers Exposed to H5N1 Bird Flu

USGS Avian Influenza in Wildlife

USGS Avian Influenza Surveillance in Wildlife

Photo credit: Wirestock on Freepik

Disclaimer: Trends content is meant to inform, educate, and inspire by providing an array of diverse viewpoints. Any content published should not be viewed as an official stance, position, or endorsement by the American Animal Hospital Association (AAHA) or its Board of Directors. 

Acknowledgement: We thank Dr. Erin Phipps, DVM, MPH, State Public Health Veterinarian at the New Mexico Department of Health, for her contributions to the situational update.