Frequently Asked Questions for H5N1 Avian Influenza and Cats » Shelter Medicine Program » College of Veterinary Medicine

This document answers common questions about H5N1 avian influenza (bird flu) in cats, including how it spreads, which cats are at risk, and what symptoms to look for.

1. What is bird flu?

Bird flu refers to the H5N1 avian influenza virus that is highly pathogenic for birds.
Wild birds, ducks and geese, and poultry are the natural host species for infection.
First discovered in geese in China in 1996.
H5N1 avian influenza virus has been infecting birds and poultry around the world since 1996.
Caused high mortality in wild birds, ducks and geese, commercial poultry farms, and backyard bird flocks in all 50 states since 2022.
The host range has expanded to a large variety of mammals, including rodents, marine mammals, squirrels, raccoons, skunks, opossums, weasels, rabbits, bears, coyotes, foxes.
For the first time since 1996, H5N1 infection was documented in dairy cattle in Texas in March 2024 and has spread to nearly 1000 dairy herds in 16 states to date.

2. How is bird flu spread?

H5N1 flu virus is shed in saliva, nasal secretions, feces, urine and milk (dairy cattle).
Direct contact with infected animals or environments contaminated by infected animals.

3. Can cats be infected by H5N1 avian flu virus?

Cats are very susceptible to H5N1 infection. This includes domestic cats, exotic species (tigers, lions, leopards, others), and wild species (mountain lions, bobcats).
First documented case in 2004 in a Thailand household of 14 cats fed raw chickens infected with H5N1 virus.
Thousands of infected domestic cats in Asia and Europe since 2004 with a dramatic spike in cat infections around the world since 2023.
First domestic cat infections in the US detected in 2022 and 2023 in outdoor cats in Montana, Nebraska, Oregon, South Dakota, and Wyoming, most of which had access to infected poultry farms.
At least 102 additional H5N1-infected cats documented from Jan 2024 to Jan 2025 in 16 states.

4. What cats are at risk for bird flu?

Cats with outdoor access in geographical locations with ongoing H5N1 flu in birds/mammals.
Cats living on dairy farms, poultry farms, or with backyard flocks.
Consumption of unpasteurized milk or other dairy products, raw poultry-based pet food, or undercooked poultry.
Cats with access to mice, dead birds.
Exposure to people who work on affected dairy or poultry farms and to their clothing or other fomites.

5. What are the symptoms in cats infected by bird flu?

H5N1 flu virus causes a severe neurological disease that mimics rabies infection. Cats can be disoriented, blind, circling, have a wobbly gait, paralyzed, or have seizures. These signs are due to virus infection of the brain. Severe neurological disease has resulted in death.
H5N1 flu virus also causes severe respiratory disease that is indistinguishable from disease caused by common pathogens such as herpesvirus and calicivirus. Cats have copious nasal discharge, coughing, open mouth breathing, struggling to breathe, rapid breathing rate. These signs are due to pneumonia from virus infection of the lungs. Cats with severe disease have died.
Some evidence that infected cats can have a milder URI-like disease with recovery.
Concern that infected cats with no disease signs can be silent spreaders of virus to other cats.

6. How is bird flu infection confirmed in suspect cats?

Suspect cats are those with neurological and/or respiratory signs from higher risk situations such as locations with known H5N1 virus circulation, contact with dairy or poultry farms or backyard flocks, or a history of consuming unpasteurized milk or raw poultry.
The only way to distinguish H5N1 from rabies or other causes of respiratory infections is through PCR testing by veterinary diagnostic labs, either state labs or national reference labs.
Cats that die from neurological or respiratory disease can be submitted to select diagnostic labs for postmortem examination, including rabies and H5N1 flu virus testing. Postmortem analyses have shown that the brain contains the highest amounts of virus with lower amounts in the lungs and gastrointestinal tract.
Swabs can be collected from the oropharynx of cats with respiratory disease for H5N1 PCR testing. However, the best practice for sampling live cats has not been established yet.

7. Can cats spread infection to other cats?

Some evidence for cat-to-cat spread of H5N1 in Asia and Europe since 2004.
Early experimental infection studies also demonstrated limited spread of H5N1 between cats.
No reported evidence of cat-to-cat spread of infection in the US but this is being closely monitored.

8. Can cats spread infection to people?

No published evidence for cat-to-human spread of infection yet but this possibility is being closely monitored.
No published evidence for human-to-cat transmission but this possibility is being closely monitored.
67 confirmed human cases in the US in 2024 linked to contact with infected dairy cattle or poultry. One person in Louisiana died from infection acquired from his backyard flock.
No evidence of human-to-human spread of infection since 2007.
At this time, CDC considers the human health risk in the U.S. to be low; however, people with close or prolonged, unprotected exposures to infected birds, dairy cattle, or other animals, or to contaminated environments are at greater risk of infection.

For more detailed information, check out the resources below.

Resources

Source: University of Florida Shelter Medicine Program, College of Veterinary Medicine. Updated 2/10/25.