You've obviously been looking after them really well, to get them to such good ages, Shirtentie. However, all otherwise healthy chickens will be carrying a worm burden to some extent., especially if they are free-ranging and thus eating earthworms, slugs and snails which are the hosts for chicken worms. Chickens are very good at hiding how they really feel, and by the time the signs of a large worm burden become apparent, they will be badly infested and this may well act as a complication if they then go down with something else because their general health and resistance to disease has been reduced by the worms. Even with lower level infestations, egg production will drop and chickens wonb't be on top form or able to get the best from their food, because it will be going to feeding the worms instead. Doing them at this time of year would be good because clearing the worms will help them to get back on top form to face the winter conditions ahead.
Of course it's entirely up to you whether or not you do worm them, but maybe your query shows that you had this in mind for the POLs at least. However, it would be better to do all of them at the same time so there are fewer worm eggs being passed to re-infect the flock. There is no egg withdrawal with Flubenvet and it is perfectly safe if you give the correct dose over a period of 7 days and make sure each bird is eating enough of it to be effective. Unfortunately one of the side effects of worm burden is loss of appetite, so if any of the flock is off her food you may need to make sure she gets an adequate dose by using the 'treats' method. Ask if you have any more problems with dosage or administration - or searce past posts, there are several threads about worming.
