Try one of these links for state vets and poultry labs near you:
http://www.metzerfarms.com/PoultryLabs.cfm
https://www.heritageacresmarket.com/blogs/misc/necropsy-list
I am sorry that you lost birds. Sometimes the neck will twist oddly right before death or with a bad disease. Do you see any bloody mucus or secretions from any birds? Such as when one slings their head around and it ends up on the walls? Use caution with DE. It can be very irritating to the respiratory system. I don't recommend it. For lice or mites permethrin is safer, used at 7-10 day intervals a few times.
http://www.metzerfarms.com/PoultryLabs.cfm
https://www.heritageacresmarket.com/blogs/misc/necropsy-list
I am sorry that you lost birds. Sometimes the neck will twist oddly right before death or with a bad disease. Do you see any bloody mucus or secretions from any birds? Such as when one slings their head around and it ends up on the walls? Use caution with DE. It can be very irritating to the respiratory system. I don't recommend it. For lice or mites permethrin is safer, used at 7-10 day intervals a few times.