Bird flu, otherwise known as avian influenza, is one of many influenza virus infections that exist. As the name suggests, this group of influenza viruses predominantly affects birds. However, incidents in the news have highlighted the ability for transmission to non-bird species. There have even been reports of the infection in pet cats. With avian influenza being present in the UK, and with over 10 million cats in ownership across the UK, should cat owners be concerned?
What are Influenza Viruses?
Viruses are grouped and named according to their characteristics (e.g. shape, genes), behaviour (e.g. how they replicate and spread), the species they infect, and the symptoms they cause. The influenza viruses typically cause respiratory symptoms and can spread through the fluid outputs of that system, typically droplets from a cough or a sneeze.
Influenza viruses are split into four types, of which type A are the most common. They are found in many animals, most notably humans, pigs, and birds. Specific proteins in the virus further divide this group into numbers associated with the letters H (for haemagglutinin) and N (for neuraminidase). The seasonal flu in people is typically caused by either of two types of influenza A virus (H1N1 and H3N2), whereas avian influenza are separate influenza A viruses.
Because of the impact to the poultry industry, those that affect birds can be referred to as low pathogenic avian influenza (LPAI) if they cause mild disease in chickens and spread slowly, or highly pathogenic avian influenza (HPAI) if they cause severe disease in chickens and spread easily. It is possible for a LPAI to mutate into a HPAI. The current globally circulating avian influenza virus is known as HPAI H5N1.
How Does Bird Flu Spread?
Avian influenza viruses occur naturally in wild aquatic birds such as ducks. They can spread between wild birds through direct exposure to infected bodily fluids including droppings, or indirectly through virus contamination of the environment. Migratory birds can carry these viruses over great distances, between countries or across continents. Domesticated birds, including farmed poultry and backyard birds, are exposed from contact with wild birds, contaminated water or contaminated footwear and gear.
This current outbreak has seen spillover into many mammal species around the world. Like birds, mammals can also be infected by exposure to virus-containing bodily fluids or through shared environments. These can be within natural spaces, or because of close proximity within farms and markets. Infection has also been linked to eating raw meat, so animals that hunt or scavenge, or are fed raw meat products could be exposed through ingestion. In the US, the virus has infected dairy cows, with raw dairy products also being linked to infection.
Bird Flu in Cats
Globally, avian influenza has infected captive big cats as well as feral and domesticated cats, although the incidence of bird flu in cats is exceedingly low. To date, it has been identified in cats in 18 countries, including the USA and parts of Europe. In the UK however, there has been no confirmed case of HPAI H5N1 in a pet cat.
Although infection incidence is low, once infected, cats do appear to be quite sensitive to the virus and can become severely ill. Unfortunately, over half of infected cats have died from the disease. If a pet cat displays any concerning symptoms, it is important to seek veterinary treatment.
Symptoms typically develop within a couple of days of infection. They include reduced energy and appetite, eye or nose discharge, difficulty breathing, neurological signs (such as uncoordinated movements or blindness), diarrhoea, and fever. These symptoms can occur with several other illnesses, including the more common infections known as ‘cat flu’ (which, confusingly, isn’t actually caused by a flu virus).
The possibility of spread between cats is not well understood but could potentially occur. Feral cats that live in colonies, barn cat populations on farms, and multi-cat households could therefore have an additional risk from being in close proximity to multiple individuals. This is expected to be a rare occurrence, however.
Transmission Between Cats and People
Since the emergence of this strain of HPAI, there have been intermittent cases of people contracting avian influenza from either birds or dairy cattle. Last year saw the first confirmed case of a cat spreading avian influenza to a human. The individual that contracted avian influenza from an infected cat did not become ill.
The risk to the general population remains exceedingly low. The risk of a person contracting avian influenza is highest in those who have occupational exposure to wild birds, farmed poultry, and dairy cattle. Those that have regular contact with cats such as the staff of veterinary clinics, animals shelters, and animal control agencies will also have an occupational risk.
Those with a compromised immune system, such as those with auto-immune diseases or those undergoing chemotherapy, should take precautions around animals. Healthcare providers can advise on individual risk factors, as well as best practice hygiene measures to limit exposure. Likewise, anyone who develops flu-like symptoms should contact their medical centre for advice or treatment.
It is unclear if, or how well, humans can transmit avian influenza to cats. Some situational infections in the households of dairy farm workers in the USA suggest it could occur, although the occurrence is likely rare.
Transmission Between Cats and Other Species
There is limited evidence of cats transmitting avian influenza to other mammals beyond people. Dogs have rarely contracted HPAI H5N1 from birds but typically have mild symptoms. There have been no cases of a cat infecting a dog or vice versa.
There have been cases of infected cats transmitting avian influenza to birds within an animal shelter. It is possible for a sick cat to infect a wild bird, however cat to bird transmission has occurred less frequently than bird to cat transmission. Households with multiple species of pet should take hygiene precautions, however the risk remains low.
Limiting Exposure Risks to Pet Cats
To minimise the risk of your cat being exposed to avian influenza, owners should avoid feeding raw meat, especially poultry, and raw dairy products. In the US, several cases have been linked to the purchase of raw pet foods, resulting in product recalls. Not feeding these types of food can therefore also control risk.
If your cat is known to hunt, you can keep them indoors or restrict their outdoor access to a catio to limit access to wild birds. Cat owners that live close to poultry or dairy farms should also consider keeping cats indoors or within a catio to prevent access to contaminants. Immunocompromised cats should be kept indoors.
Owners who venture into very rural or wilderness areas for work or recreation, should change footwear and clothing upon returning home, and disinfect shoes and gear regularly. These items should also be kept out of the reach of their cats. General hand hygiene around human and pet food preparation is also advised to limit disease exposure.
Regional news and government websites can be consulted to monitor avian influenza outbreaks in your area. Higher precautions, including avoiding at-risk areas, should be used if case numbers increase.
Conclusion
Avian Influenza A H5N1 has been identified in birds and mammals around the world. Although predominantly an infection of birds, both wild and domestic cats have contracted the disease in several countries. The transmission risk to cats remains exceedingly low, however some lifestyle and feeding habits increase the risk to some individuals. When cats become infected, the disease can be severe and even fatal. Despite this, the risk of cats spreading bird flu to other animals, including humans, is rare.
Further Reading:
Avian Influenza in England – DEFRA
APHA Surveillance for Avian Influenza in Wild Birds and Wild Mammals in GB – DEFRA
Avian Influenza in Cats – WOAH
Avian Influenza and Cats – iCatCare
Cat deaths linked to bird flu contaminated raw pet food sparking voluntary recall – AVMA
Bonilla-Aldana, D.K., Bonilla-Aldana, J.L., Acosta-España, J.D., and Rodriguez-Morales, A.J. (2025) ‘Highly Pathogenic Avian Influenza H5N1 in cats (Felis catus): A systematic review and meta-analysis’ Animals, 15(10), pp. 1441.
Coleman, K.K., and Bemis, I.G. (2025) ‘Avian influenza virus infections in felines: A systematic review of two decades of literature’ Open Forum Infectious Disease, 12(5).
Schlachter, A.D., Bruno-McClung, E., Díaz-Delgado, J., Odom, M., Banyard, A.C., and Núñez, A. (2025) ‘Feline high pathogenicity avian influenza H5N1 infection: past and present’ Journal of Feline Medicine and Surgery, 27(10).
Vaughan, A., Joyce, A., Traub, E., Jae, M., Beeler, E., Paiva, E., Ananian, K., Holiday, C., Jefferson, S., Richardson, J., Munna, C., Chan, C., Scott, T., Kojima, N., Seneviratne, T., Mellis, A., Olsen, S.J., Green, N., Feaster, M., Terashita, D., Balter, S., Levine, M.Z., Middleton, J., and de St. Maurice, A. (2026) ‘Serologic evidence of Highly Pathogenic Avian Influenza A(H5N1) virus infection in a veterinary professional exposed to an infected domestic cat — Los Angeles County, California, December 2024–January 2025.’ CDC Morbidity and Mortality Weekly Report, 75, pp. 215–220.
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