Infestation with fleas is not uncommon. The fleas themselves are quite difficult to spot, and diagnosis is often made from the flea dirt (little black specks that remain on the animal). Fleas may cause the puppy to scratch, especially if the pup is hypersensitive to the flea saliva. Flea infestation requires treatment, because it can affect us humans too. Your vet will help in the diagnosis, and advise you on a course of treatment for the pup and for the environment.