Avian influenza, commonly known as bird flu, has long been recognized as a threat to avian species and, occasionally, humans. However, recent cases have highlighted another susceptible group: domestic and wild felines. The H5N1 strain, in particular, has shown the ability to infect cats, raising concerns about cross-species transmission, public health implications, and animal welfare.

What is Avian H5N1?

H5N1 is a highly pathogenic avian influenza virus that primarily affects birds. First detected in the late 1990s, it has caused significant outbreaks in poultry worldwide. While primarily avian-focused, the virus has demonstrated zoonotic potential, meaning it can spread to other species, including humans, felines, and other mammals. The biggest carriers are migratory waterfowl (89 avian species) and 45 mammalian species.

How Do Cats Get Infected?

Cats primarily become infected with H5N1 through:

• Ingesting infected birds: Outdoor cats that hunt and consume infected wild birds are at significant risk.

• Direct contact: Cats near infected birds or poultry farms may contract the virus through droppings, saliva, or contaminated surfaces.

• Inhalation of aerosolized particles: In rare cases, the virus can spread through airborne particles.

• The sources of the most recent infections in cats have been traced to ingesting raw dairy products (milk and cream) and raw meat.

Clinical Signs in Felines Cats infected with H5N1 may exhibit various symptoms. Consider testing for avian influenza type A (H5N1) in cats if ANY of the following are noted in a cat or a group of cats:

• High fever

• Respiratory distress (e.g., coughing, sneezing, difficulty breathing)

• Lethargy and weakness

• Neurological signs such as seizures, tremors, uncoordinated movement, circling, confusion

• Sudden death in severe cases

• Signs that look like rabies infection

It’s important to note that not all infected cats will display symptoms immediately, which complicates detection and containment. There have been about 54 reported cases in cats, and the mortality rate is >67% at this time.

Risk to Humans

While there is no evidence of feline-to-human transmission of H5N1, the virus's mutability poses a theoretical risk. Humans in close contact with infected cats, such as pet owners, veterinarians, or animal shelter workers, should practice strict hygiene measures to minimize exposure.

Preventive Measures

• Keep cats indoors to reduce exposure to infected birds.

• Avoid feeding cats raw meat from any source (per the USDA).

• Monitor any unusual symptoms and consult a veterinarian if illness is suspected.

• Follow biosecurity protocols if working with birds or poultry.

• Isolate cats who exhibit newly developed neurologic signs with an unknown history.

Research and Surveillance

Research on H5N1 in felines is ongoing, with scientists focusing on understanding the virus's behavior in mammalian hosts. Enhanced surveillance and reporting mechanisms are critical to detecting outbreaks early and preventing potential cross-species transmission.

Conclusion

Pet owners, veterinarians, and public health officials must remain vigilant, prioritize preventive measures, and contribute to research efforts to mitigate the risks associated with this virus. Any cat showing the symptoms mentioned above should see their vet immediately.

Resources:

Refer to this site to see the species affected: https://www.fao.org/animal-health/situation-updates/global-aiv-with-zoonotic-potential/bird-species-affected-by-h5nx-hpai/en.

Recommendations for monitoring and response to possible infections with avian influenza type A (H5N1) in cats for shelters, rescues, and access-to-care clinics https://docs.google.com/document/d/e/2PACX-1vTlPL2hF3RrDVecqLsF0Viztp38eJEUSZpsJDNAYG1Rfun8pJuafOxXRLJZy5QiK0GZkrP18gbBeBr4/pub.