H5N1 bird flu has spread to millions of poultry birds all across the country and more than 900 dairy herds across 16 states. According to the U.S. Centers for Disease Control and Prevention, there have also been 67 confirmed cases in people, along with one death. Now, officials are warning about deaths in cats.

According to a CBS News report, the U.S. Food and Drug Administration says it’s currently aware of 13 domestic cats in eight households that have either been sickened or died due to bird flu. This is in addition to an exotic cat in one household and an unknown number of big cats at two different sanctuaries. The cases were recorded in California, Colorado, Oregon, and Washington State.

The illnesses have been linked to contaminated raw food products. The FDA says it’s currently working to trace the source of the outbreak. Until then, the agency has ordered manufacturers of uncooked or unpasteurized dog and cat food to update their food safety plans to include the threat of Highly Pathogenic Avian Influenza.

In a statement, the FDA said, “Scientific information is evolving, but at this time it is known that H5N1 can be transmitted to cats and dogs when they eat products from infected poultry or cattle (e.g., unpasteurized milk, uncooked meat, or unpasteurized eggs) that have not undergone a processing step that is capable of inactivating the virus, such as pasteurizing, cooking or canning.”

Though the order relates to dog food, as well, there have not yet been any confirmed cases in dogs within the United States. It’s also not as deadly in dogs as it is in cats. Even larger cat species face more severe disease.

The FDA is encouraging pet food manufacturers to use ingredients from healthy flocks or herds and to use processing steps capable of inactivating viruses, such as heat treatment.

For tips on keeping your pets safe from bird flu, click here.