Here in South Florida the yard is like a big petri dish filled with all sorts of microscopic life. I try to keep everyone healthy enough to resist being adversely affected by such things. But occasionally I know they need a little help from a bottle. When I see roundworms waving "howdy!" to me from somebird's poop I know that there must be others harboring similar company. All my birds mingle & eat & drink from each other's dishes and there's not much I can do to change that.
Each morning I let the ducks & geese out of their houses & pens and they roam the yard all day. They have pans of water they drink from as well as their kiddy pool. And the chickens also drink from those pans, especially the bantam flock who roost in the trees & roam the yard all day.
I cannot confine the Khaki Campbell ducks to their pen (they fly over the fence) but I could keep the Pekins & the geese confined, with Wazine-free water for the day. But then the bantams wouldn't get the Rx they need if they drink from the ducks' pans.
I could instead let the ducks & geese out of their pens, and just let them drink from the pool all day. And put the Wazine-treated water pans IN the pens and close them off from the ducks & geese for the day. That way the ducks & geese would have NO access to Wazine and also wouldn't be stressed by being confined all day.
That is, unless it would be advisable to dose the ducks & geese with Wazine, which was my original concern. I haven't started the treatment yet because I've been sick inside with a bad head cold. Any more imput would we welcomed on this matter, thank you!