Recommended for worming of Puppies from 8 weeks of age then regularly, 3 or 4 times yearly to keep Puppies and Dogs worm free. Johnson’s One Dose Easy Wormer are available in 4 sizes-from puppies and small dogs, to medium, large and very large dogs (or homes with more than 1 dog).ost responsible dog owners know that they should be worming their dog but there are many myths regarding why to worm, how often to worm and what to worm with.