I wouldn't use the Panacur Paste on any of mine and haven't done for a couple of years now. There have been some bad reports about it over the years and I remember a thread on one of the forums about it a couple of years ago, where the paste had caused numerous stomach problems in kittens and the end result was, they had to be pts. I would recommend hanging on until they were 6 weeks, making sure they are within the weight and worm them with Milbamax.