When do new puppies have to be wormed?

Due to the high incidence of parasitism in puppies and the extended period of time that environmental contamination can lasts and the risk to humans from the most common GI parasites of puppies, the Center for Disease Control recommends that puppies be started on a preventative deworming program at 2 weeks of age and continued on it every 2 weeks until they are at least 8 weeks of age. Most heartworm preventatives are also labelled effective against hookworms and roundworms (the most common GI parasites in puppies) so once a puppy is started on heartworm preventative he will be getting a preventative deworming monthly.