Because on Apr 12, just 10 days after CDC published "Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations" that said:
"...should avoid unprotected direct physical contact or close exposure w/sick or dead birds or other animals, carcasses, feces,
milk
or litter from sick birds or other animals potentially infected or confirmed to be infected w/ HPAI A(#H5N1) virus."