Ivermectin can be given orally to chickens. You can use the injectable Ivomec, 1% solution(labeled for cattle and swine) at .01 cc per chicken orally or injected subcutaneously.
Plumb's Veterinary Drug Handbook states: "Most birds: inject 220 mcg/kg IM or orally"
Heartgard also contains...
We painted/sealed our coop inside and out with an opaque fence stain/sealer and it has worked wonderfully so far. I think the product is from Behr. It comes in lots of colors; we picked a nice sage green. We got it at Home Depot. I cover the inside of the sleeping/nesting/roosting area with...