Avian influenza viruses circulate naturally in wild aquatic birds. They are extremely contagious and can also infect domestic birds. But since 2020, we have observed an increase in cases of infection among wild and domestic mammals. The Los Angeles County Department of Public Health recently reported new cases of cat infections. They would have consumed contaminated food.
Indeed, avian flu recently affected several herds of dairy cows in the United States. In June 2024, the U.S. Department of Agriculture reported the detection of dozens of H5N1-positive house mice and four house cats in Roosevelt County, New Mexico. To date, about ten states have reported cases of infected cats. Los Angeles County has just confirmed the detection of the virus in seven cats. These pets had consumed milk and raw food.
Raw animal food potentially involved
“ Five cats from one household developed acute illness after consuming two brands of commercially available pet food », Indicates the press release. These were cats living exclusively indoors. Experts therefore quickly considered their diet – based on raw foods – as the probable source of the infection.
About one to two weeks after starting to consume these pet foods, all five cats developed symptoms. Two of them were in severe respiratory distress and had to be euthanized. Other symptoms included upper respiratory tract involvement, lethargy, decreased appetite, frequent urination, motor disturbances and eye conditions leading to permanent vision loss.
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In a second outbreak, an indoor cat also developed the onset of acute illness after consuming three different brands of raw poultry foods. He presented with fever, lethargy, anorexia and wheezing. Tests confirmed infection with the avian flu virus. He was put on oxygen for several days and recovered. The family that owned the cat and the staff of the veterinary clinic who treated it are being monitored for possible flu symptoms.
A raw food product, from the “Monarch Raw Pet food” brand, tested positive for avian flu. It contained live H5N1 virus. This product is sold in several stores in Southern California. The investigation continues and Food and Drug Administration (FDA) is currently testing food products from other brands, which have resulted in symptoms in cats.
Feline infections confirmed in several states
The public health department's press release also reports several other infected cats, from two separate outbreaks. They became ill after consuming raw milk intended for human consumption. This milk was recalled due to H5N1 contamination.
In early December 2024, seven cats from one household became ill and five died. A few days later, a cat from another home died following the appearance of serious neurological signs (anorexia, disorientation, ataxia, confusion and convulsions). The veterinarians first performed a rabies test, which came back negative. A brain sample, analyzed by the National Veterinary Services Laboratories (NVSL), ultimately confirmed an H5N1 infection.
“ Further investigation revealed that this cat lived in a household of eight indoor-outdoor cats who had been offered milk from Raw Farm LLC in late November 2024; however, the number of cats that consumed the raw milk in this household was unclear », Specifies the press release. Over a three-day period, three of the eight cats in this home became seriously ill and died.
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These are the first confirmed cases of cats infected with the H5N1 virus in Los Angeles County. Authorities have recorded numerous probable cases of bird flu in cats that had consumed raw pet food or raw milk. However, it was not possible to test all of the animals, the county press release points out. Other confirmed cases of infection are coming in from across California and other states.
Health authorities recommend that pet owners not feed them raw dairy products, raw meat, or any other raw foods. They should also be kept away from wild animals.
What are the risks for humans?
Avian flu today affects a wide range of animal species around the world. This includes skunks, foxes, mountain lions, bears, raccoons, opossums, bobcats, coyotes, seals, river otters, baby goats and dolphins. The first case of a dog infected with H5N1 was reported in April 2023 in Canada. He had chewed a dead goose.
Detection of H5N1 virus in wild and domestic mammals, in the United States, from May 2022 to date. Credits: US Department of Agriculture
Cat contamination does not only concern the United States. Several countries in Southeast Asia and Europe have reported infected cats, including France. The susceptibility of cats to highly pathogenic avian influenza viruses (HPAI) has been known since 2004, according to ANSES. The first French case was confirmed at the end of 2022: the cat in question lived near a duck farm.
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Pierre Bessière, virologist at the National Veterinary School of Toulouse, recently became interested in the transmission of avian flu in cats. Of the approximately 600 blood samples tested, 13 tested positive for the virus. “ If we extrapolate these results to that of the total population, between 0.5 and 1% of French cats may have encountered the virus at some point in their lives. “, he said. Cats that have access to the outdoors are obviously at greatest risk of contracting the disease.
Despite the situation, American public health officials want to be reassuring. “ Currently, there is no evidence of local cat-to-cat, cat-to-human, or human-to-human spread of avian influenza, and the risk to the general public remains low. », they recall. Nonetheless, this spread among mammalian species indicates that the H5N1 virus mutates to adapt to each. The risk is that it will one day manage to spread from human to human.
According to the World Health Organization, since 2003, there have been nearly 900 cases of human H5N1 infection worldwide. Half were fatal. For now, people who are in close contact with animals, particularly wild birds and their droppings, infected cats, infected poultry or infected dairy cows or their milk, remain at greatest risk.
With an unwavering passion for local news, Christopher leads our editorial team with integrity and dedication. With over 20 years’ experience, he is the backbone of Wouldsayso, ensuring that we stay true to our mission to inform.
