I found this helpful, from an old thread ....
https://www.backyardchickens.com/forum/viewtopic.php?pid=2525157#p2525157
Quote:
You sound experienced - you're certain it was a roundworm - not a tape? Because the treatment would be different? I just want to "dot my i's and cross my t's" here.
It wasn't flat and segmented, but thin and round?
Piperazine's (Wazine) mechanism of action is indeed that it paralyzes the worm, causing it to be expelled. Roundworms do not live for very long outside their host. So you need not be concerned about having to retrieve them. But that's one reason why I follow up with something that DOES kill them.
They do also excyst and travel, as larvae, to the lungs of the animal at one point in their development. From there they are coughed back up and reenter the digestive tract where they become adults. There they are treatable by all roundworm-effective antihelmintics. You likely know this, but this is more for someone else who might read this and not know.
If you see a bird passing a worm, it's more likely that they have a large infestation since (as you well know) you will otherwise rarely see worms in poultry. So really, unless you do a fecal egg count to show how many eggs are being shed, one must assume there COULD be a large number of worms both in the intestines and the lungs.
If you kill all of the roundworms at once, then you have these dead worms that need to be expelled. If a bird's body is presented with a high number of dead worms, they can sometimes have an anaphylactic reaction to what has essentially become a "foreign protein" in their body. Alternately, there have been cases where a large number of dead worms being expelled from the body have caused blockage.
So that's why I always recommend Wazine first. If there are a large number of roundworms (and again we have to assume it's possible unless proven otherwise by an egg count), then you won't risk the "dead worm" foreign protein effect. Because Wazine is a repeated wormer, it's less effective and you won't overload the bird with passing worms if there's a huge infestation. If there are few, you might just get them all. But it's meant to be repeated.
Instead of repeating the wazine, I like the more broad spectrum wormers that also effect cecal worms, and even external parasites, and actually paralyze as well as KILL the parasites. I'm not sure whether or not it works on the lung parasites, and would suppose it depends on the wormer. Personally I use pour-on ivermectin which doesn't go through the digestive system but through the tissues. So it would be most likely to do so. I'm looking that up now actually because I don't know. It says "immature" but I'm not sure they mean in the lungs, though I really think they do.
But since ivermectin (and fenbendazole, and levamisole, and other broad-spectrum wormers) DO kill a number of other parasites (that may not shed through the feces) I like to knock down the numbers first with wazine. Also because ivermectin kills adult and immature roundworms, I take the safe gamble and do the weaker treatment first. Then go back and blast both adult and immature worms.
I hope that makes sense.
