Highly pathogenic avian influenza, HPAI, and bird flu are all different names for the same virus, and H5N1 is one strain of the virus. The outbreak of H5N1 started in 2022 and has been front-of-mind for many because the first severe case in a person was reported in Louisiana in December 2024 and the first fatality in a human was reported in California in January 2025. 

Dr. Graham Brayshaw, Chief Medical Officer, breaks down the details of what H5N1 is, what animals are affected by the virus, what symptoms to look for in your pets, and where to find more information.  

What is it?

H5N1 is an influenza virus type A. It causes respiratory symptoms in most species it infects. It is originally spread by migratory birds and becomes an issue when it expands into commercial flocks. It is especially impactful on the turkey and chicken industries in Minnesota.   

Influenza viruses like to mutate and can jump species, with some species getting sicker than others. This strain became worrisome when it was found in multiple dairy herds across the country — spreading in new ways compared to previous outbreaks.  

Most transmission is from infected animals coughing and sneezing. Fortunately, influenza virus does not live well outside of its host, so indirect spread from surfaces is rare. Most cleaning products will kill the virus. In addition to cows, cats also seem to be particularly susceptible to this virus.   

What animals are impacted by this disease? 

There are five groups of species we’re currently watching:

• Wild birds: This is the original source of this virus. Transmission from these birds to poultry, cats, and cattle has been documented. Wild birds regularly get sick and can die from H5N1 infection.  
• Poultry: This is where the biggest impact of the virus has been observed, with over 100 million chickens and turkeys affected! They usually catch the virus from wild birds or cattle and appear to transmit it to people. Poultry can get very ill and die from this infection.  
• Cattle: This virus appearing in dairy cattle was unexpected. Over 700 dairy herds, including nine in Minnesota, appear to be infected. Cattle can infect each other and likely first caught the virus from wild birds. Cattle have been known to infect people, poultry, and cats.
• People: There have fortunately been very few infections in people to date, mostly individuals exposed to a lot of sick animals. As of January 2025, H5N1 has been diagnosed in 67 people, with 63 of them being exposed to dairy cattle or poultry. Most people have had mild symptoms, however one person died and another individual got very ill.  
• Cats: Similar to cattle, this virus appearing in cats was unexpected. Cats don’t appear to easily transmit this disease to other species and have caught the virus from direct exposure to dairy cattle and wild birds. They can also be infected by eating raw diets and drinking unpasteurized milk. Cats get very sick from H5N1, with over 50% dying even with treatment. Unique to other species, cats show neurologic signs, like seizures, in addition to respiratory symptoms.  
• Dogs: There have not been any reports of this disease in dogs. Officials aren’t currently worried about dogs catching the virus or transmitting H5N1 to other animals.   

To understand spread of the disease, the CDC published this helpful graphic: 

What should I care about it and what should I do? 

Even if you don’t interact with cattle or chickens, it's recommended to be aware of what’s happening with H5N1 since the virus can spread to humans and cats. We want to provide reliable information so you can make informed decisions for you and your pets.

For cats, we recommend the following:

• Limit your cat’s exposure to potential sources of this disease.
• Avoid feeding raw diets and unpasteurized milk to your cats.
• Keep your cats indoors and away from barns that may have infected cattle or poultry or wild birds that may carry this disease.
• If your cat is sick, contact your vet immediately.   

For humans: We aren’t qualified to provide recommendations on human health. We recommend talking with your doctor and gathering information from reliable sources like the CDC and Minnesota Department of Health.   

Want to know more? 

These are reputable agencies that provide accurate and up-to-date information: 

• The CDC has extensive information, with individual pages dedicated to each of the significant species affected by the outbreak.
• The Board of Animal Health is leading the state response to this virus, and they have the most up-to-date local information on the outbreak.
• The University of Minnesota publishes regular reports on HPAI through their Center for Infectious Disease, Research, and Policy.