Ivermectin will treat Mites on the birds, but if won't help with those that are in the coop/housing. You can use Elector PSP in the housing to help elimate them. Dosing for Ivermectin is below.I gave the hen who's not doing well some heart for iron.
I have two cats, so Permethrin isn't really an option for me. Do you know the dosage for Ivermectin? I have some dog ivermectin available.
I do have this. chicken de-wormer Could that help at all?
Personally, I would use an Anthelmintic like Fenbendazole to deworm. Safeguard 10% Liquid Goat Dewormer can be found at TSC. Dose is 0.23ml per pound of weight given orally once daily for 5days in row.
https://www.backyardchickens.com/threads/mites-lice-now-hen-growling.1242981/post-19965544