I reread your post and you say it is chicks that you are treating. I would definitely use the permethrin powder. Anything else may be too potent for baby chicks.
@DobieLover has given you excellent advise.
I have cats, 2 of them are outdoors and go in and out of the coops and runs. I do use permethrin for my flock and my cats have not been harmed. I believe it is safe to use as long as you do not apply it directly to the cats.
If you are still...