Here are some good articles on canker (trichmoniasis: http://www.poultrydvm.com/condition/canker
http://www.chickenvet.co.uk/health-and-common-diseases/digestive-problems/index.aspx
https://www.merckvetmanual.com/poultry/trichomonosis/overview-of-trichomonosis
http://www.chickenvet.co.uk/health-and-common-diseases/digestive-problems/index.aspx
https://www.merckvetmanual.com/poultry/trichomonosis/overview-of-trichomonosis