Interceptor Spectrum Tasty Chews for medium dogs are monthly tasty chews for the prevention and control of heartworm and intestinal worms in dogs. Interceptor will prevent heartworm and control roundworm, whipworm, hookworm and adult tapeworms in dogs. They can be safely used in puppies from 2 weeks of age, breeding males and females, as well as pregnant females but get your dog heartworm checked if starting this product on a dog older than 6 months or if it has been more than 60 days since last heartworm prevention treatment. Interceptor Spectrum is to be given monthly, preferably on the same date each month.