Monthly wormer treatment is recommended for pets who love the outdoors or eat raw food because they're much more likely to get worms. Children under 4 and the immunosuppressed are in danger from a pet with worms, so monthly treatment is also recommended here. All other pets are recommended a quarterly wormer treatment programme. For convenience, you can subscribe to worming treatments like Itch Wormer Tablets for Dogs and Itch Wormer Tablets for Cats, which sorts all the timings out for you.