Clients have found these articles about equine euthanasia and cattle euthanasia useful
Guidelines for equine euthanasia
https://aaep.org/horsehealth/aaep-guidelines-euthanasia-2011
AVMA Guidelines for the euthanasia of animals
https://www.avma.org/KB/Policies/Documents/euthanasia.pdf
Practical euthanasia of cattle
http://www.aabp.org/resources/AABP_Guidelines/Practical_Euthanasia_of_Cattle-September_2013.pdf