Is it safe to worm a cat while it is breast feeding her 5 kittens that are now about 4 weeks old? I believe the kittens most likely have worms as well and ive been told that you have to worm all the animals at once in order for them to fully go away but I can't worm the kittens yet because they are not old enough but the mother cat needs to wormed badly because she is basically only pooping out worms.