Go out to your coop(s) in the dark before sunrise when your birds are roosting. They cant see in the dark and bring a flashlight with you. Bring the Valbazen with you and the syringe.
Snatch a bird off the roost one at a time and worm them with your preloaded syringe.
Cradle the bird in your...
Valbazen isnt prescription. Your local feed store might carry it. You can order Valbazen in this link if you wish:
https://www.valleyvet.com/ct_detail.html?pgguid=30E07949-7B6A-11D5-A192-00B0D0204AE5
Dosage is 1/2ml given orally for a 5 pound bird using a syringe without a needle. Then repeat...