Here are some articles about botulism to compare with wry neck:
https://nt.gov.au/__data/assets/pdf_file/0010/233569/botulism-in-chickens-ducks-and-others.pdf
https://www.merckvetmanual.com/poultry/botulism/botulism-in-poultry
https://nt.gov.au/__data/assets/pdf_file/0010/233569/botulism-in-chickens-ducks-and-others.pdf
https://www.merckvetmanual.com/poultry/botulism/botulism-in-poultry