Bird flu spreading to indoor cats

How did this happen?

The CDC finally published a report in their Morbidity and Mortality Weekly Report (MMWR) regarding the potential spread of highly pathogenic avian influenza (aka bird flu) amongst indoor cats. This post will summarize some of the findings in the report but the link is above if you want to read it in its entirety.

In May 2024, a 5-year-old cat that was exclusively indoor, spayed female domestic shorthair, experienced decreased appetite, lack of grooming, disorientation, lethargy and then neurologic deterioration. On the second day of illness the cat was taken to their local veterinarian. By the fourth day, the cat was taken to Michigan State University (MSU) and was euthanized because of the rapid health decline. Their remains were tested positive for bird flu, specifically genotype B3.13.

This cat lived with two adults, one of whom worked on a dairy farm in a county known to have bird flu-positive dairy cattle. There were also two teenagers and two other indoor cats. One of the other cats was sick with respiratory symptoms and decreased appetite but was not tested for bird flu. The third cat was tested and was negative for bird flu. The dairy worker declined bird flu testing while the other three family members tested negative for bird flu.

Six days after the first cat was referred to MSU, an exclusively indoor intact male Maine Coon cat that was 6 months old at another household was brought into the MSU clinic with 1 day of progressive neurologic deterioration, anorexia, lethargy, and facial swelling. The cat died within 24 hours of the onset of illness. This cat had lived with another indoor cat and its owner who was a dairy farmworker. His owner transported unpasteurized milk from various farms in a county that had confirmed bird flu cases amongst dairy cattle. The owner did not wear personal protective equipment (PPE) while handling raw milk and reported frequent milk splash exposures to the face, eyes and clothing. This person declined bird flu testing.

While bird flu cases amongst indoor cats is rare, cats can pose a risk of infection to humans. It is unclear how these cats got infected, but it may have been through the dairy farm work. There may have been some type of fomite transmission that the dairy workers brought back into their homes.

The CDC in this report recommends farm workers to consider to remove clothing and footwear and wash off any animal byproduct residues before entering households. Veterinarians evaluating cats for respiratory or neurological illness should wear PPE during examination. In addition, anyone who works with poultry and wild birds should wear PPE when interacting with potentially infected animals.

The risk to the general public is still low, but we need to stay informed to understand what steps may need to be taken to help stay healthy.

---

Subscribe to stay informed. While not required, any support is greatly appreciated.