It is not free in Ca anymore... I believe the current cost is $20/2 birds... just the necropsy, not the euthanasia.In California and a couple other states necropsies are free
Here are some links that show how to send them off if shipping is needed and a list of the labs here in the US..
https://www.backyardchickens.com/threads/how-to-send-a-bird-for-a-necropsy-pictures.799747/
https://www.aphis.usda.gov/animal_health/nahln/downloads/all_nahln_lab_list.pdf
@Homestead Woodwright adding your general location to your profile can help others make the most relevant suggestions at a glance.
