what are we doing wrong?

[livininbrazil]

Here is a name for a good wormer you can just put in a syringe about 1/2 cc for a medium size goose. It is called Eprinex (a liquid wormer Ivermectin) for cattle. You put the 1/2cc between the two wings. My friend on another forum taught me about this womer.
You worm before the end of Fall and before breeding starts in the Spring.

I´ll have a look to see if it´s available here. The one I use for my birds is called Proverm, it seems to be a vermicide for just about all animals. Sometimes Panicur is available. I´ve never seen a worm in their poop, and I clean up after them nearly every day, but I worm them anyway, especially because of the dangers of gapeworm.