
I hope you have wormed them before this? You should start worming puppies at 3 weeks of age. Don't know about the intervals with Panacur but with Drontal you do it every 2 weeks. Some start as early as 2 weeks of age. Personally I do 3, 5, 7 weeks and then ask the new owners to continue at 9 weeks and 11 weeks.
If the puppies are fighting, are you sure that a) it isn't just in play? b) as they are a large breed, do they have enough space? By 8 weeks of age they will certainly need to be able to have a good romp around the garden and won't want to be kennelled all the time, and they are of course also ready to go to their new homes.
Marianne