What a coincidence for me that this thread was started.
I have mentioned we have problems with worms in our pigeons and have one bird that is staying in the house over winter because of a very bad infestation. This bird (******) has been treated with Pyrentel, Panacur and Ivermectin and, I think, finally has them licked. She weighed the most tonight since we brought her in Thanksgiving Day.
Our problem is that we have a dirt floor in our aviary. We use wood chips on top of that and change the chips out at least every 3-4 weeks and spot change under the perches inbetween. Since we rehab, the original concept was that the birds would be in the aviaries for a short period of time, then released. We were told that a dirt floor would be best. However, even with the best of intentions, we now have about 30 pigeons that we call "keepers" either because of health issues or simply because we grew too fond of them to release. We also have several white pigeons that we don't release because of hawk issues. Our vet believes that over a period of years a worm "colony" has been established in the soil.
Our vet told us a few weeks ago she wanted to talk with a colleague in Oklahoma about our problem. She called me today and said this doctor (who also raises pigeons) advised us not to put in a wood floor. Instead, he suggested we remove at least 1" of soil from the floor and replace with 2" of sand, or, remove 2" soil and replace with 4" of sand, 2 x year. My vet said considering our climate she thinks we should do it more often. Apparently, the constant removal of soil will remove the worm eggs. Her colleague also wants us to continue to use Pyrentel as the wormer of choice. (I didn't think to ask if she discussed Panacur with him but I'm to see her tomorrow and will find out.)
Anyhow, I thought it interesting this thread came up.