Google trends. Ask it questions like “why is my cat bleeding” or “why is my dog bleeding” and look at trends and localization over the last 3mo. Search in both English and Spanish to capture data from native Spanish speakers (the bulk of the workforce at meat processing plants) and their extended communities.
Google h5n1 symptoms in cats and dogs (bleeding from the eyes, ass, high fever, pink eye, seizures, etc) and come up with queries that everyday people might Google (like: “why is my dog bleeding from his privates” because Americans can’t say “anus”) and go from there.
I haven’t really kept track of all of the queries we looked through over the last couple of months, this was more my SO’s thing. Epidemiologist Twitter probably has some good data too.
Off the top of my head pink eye in dogs, cats with seizures, cats bleeding from their eyes, dogs bleeding from the ass, high fevers, etc all had pretty narrow localization around major industrialized meat packing plants or industrial scale livestock farming.