Worming Chickens

My chickens have not been looking very healthy lately and one of the older hens even had a bit of diarrhea. I make one of my frequent trips to the feed store and it was recommended that I worm them. Now I am certainly not new to country life, but had never even heard of worming chickens. I don't know why it never occurred to me as I worm everything else.
I buy a bottle of Piperazine-17 and get it home to find out there is nothing about chickens on the bottle. Thank God once again for the info on the Internet. I find out I put 1/2 tsp in 4 cups of water. After pulling their water the night before I put in the medicated mixture and keep them in the pen until they drink almost all of it. We can't eat the eggs for 2 weeks but I am giving one a day to the dog as I figure it won't hurt him. The chickens look better and the diarrhea cleared up very quickly.

I plan to do it again in the fall. I have an 8 oz. bottle of this stuff and using it 1/2 teaspoon at a time I think it is a lifetime supply.