DOMESTIC CATS IN COLORADO ARE DYING OF BIRD FLU. IS YOUR CAT AT RISK?

In Colorado this year, several house cats have died from bird flu, with some cases lacking any direct contact with outbreaks on dairy farms.

State public health officials have not yet determined how Highly Pathogenic Avian Influenza H5N1, which has affected infected herds, led to illness in six domestic cats, including two that were indoor pets. This raises questions about the virus’s modes of transmission and how it affects various animals.

Kristin Richmann, a spokesperson for the Colorado Department of Public Health and Environment, noted, “We suspect the infections are related to exposures on dairy farms.” She explained that genetic testing of the virus has linked some of these infections to the avian flu outbreak among dairy cattle, though direct exposure to dairy cattle was not documented in all cases. For the two indoor cats, Richmann suggested that the virus might have been introduced into the home environment, leading to infection.

Experts suggest that the deaths of these cats might be related to mice carrying bird flu that entered homes. Cats could have caught the virus by preying on these rodents, an occurrence that pet owners might not notice, according to Dr. Jane Sykes, a professor of small animal internal medicine at the University of California, Davis. Another possible source of infection could be raw food given to pets.

While some cats on farms with infected livestock have died from bird flu this year, the transmission to house cats with no direct exposure to sick animals remains unclear.

Dr. Sykes noted, “When you see a small number of reported cases, it’s often just the tip of the iceberg. There are usually many more cases that go unrecognized.”

Bird flu in cats, humans

The risk of bird flu to the public is low, state and federal officials say. It’s also unlikely that sick pets would transmit the virus to humans. There has been no transmission of the virus between people during this outbreak.

Last week, the Colorado State Veterinarian’s Office announced that six domestic cats had been diagnosed with H5N1.

According to the Colorado Veterinary Medical Association, one of the cases was linked directly to a commercial dairy facility with infected cows. Two of the affected cats were indoor pets, while the remaining three had spent time outdoors hunting mice or small birds.

Five of the six cats exhibited similar symptoms. Pet owners initially noticed lethargy and loss of appetite in their cats. As the illness progressed, many developed severe respiratory issues and neurological symptoms. Although several cats were tested for rabies due to the similarity of symptoms, all results were negative. Ultimately, all six cats died and tested positive for bird flu.

According to the state veterinarian, the virus from nearby dairy herds has spread to mammals and wild birds in and around these areas. The particular strain of H5N1 has begun affecting species that were not previously known to harbor the virus.

Colorado Public Radio, referencing data from the U.S. Department of Agriculture, connected five of the six cats to northern Colorado, an area with reported livestock outbreaks.

The USDA’s National Veterinary Services Laboratory confirmed that 36 domestic cats have tested positive for bird flu. In many instances, these cases involved the same strain found in dairy cattle.

Across the U.S. this year, 13 people have been infected with bird flu, including 10 in Colorado. All were poultry or dairy workers. No person has become ill from an infected cat, said Richmann, from the state public health department. Officials have monitored people exposed to the sick cats for 10 days after their last exposure, she said.

Cats are generally considered “dead-end hosts” for bird flu, meaning they usually do not pass the virus on to other animals once infected, according to Dr. Jane Sykes from UC Davis. The death rate among infected cats has been high, with about two-thirds succumbing to the disease, as reported in one study.

However, there have been rare instances of cats transmitting the virus. In 2016, a cat at a New York City animal shelter transmitted a different strain of avian influenza to a person. Previous outbreaks have also occurred in Thailand and Germany.

Jennifer Martin, an assistant professor of epidemiology at the Colorado School of Public Health, emphasized the importance of understanding the genetic sequence of H5N1 in cats. This knowledge is crucial to determine whether the virus is mutating or simply finding new hosts it is already adapted to.

“Understanding whether the current situation is due to changes in the virus or just natural expansion will be key,” Martin said. “Once we have that clarity, we can implement the best practices to address the issue effectively.”

What can I do to protect my cat?

How much the bird flu has spread beyond infected farms remains unclear. In the meantime, the public should rely on established methods to protect people and their pets from getting sick, Martin said. These steps are as simple as washing hands after handling food or litter boxes. Pet owners should also avoid serving their pets raw milk or meat. The Centers for Disease Control and Prevention recommends people and pets avoid contact with wild birds.

Pet owners should watch for signs of illness in their cats and should contact a veterinarian if respiratory and neurological symptoms develop. The Colorado Veterinarian’s Office said bird flu infection should still be considered in cats even if symptoms and risk factors aren’t all present.

People get sick when they inhale the virus or get it in their mouth, eyes or nose. In humans, symptoms have included eye redness and flu-like respiratory issues.