Can puppies really be born with worms? Veterinary Services Department, Drs. Foster & Smith, Inc. Font Size: [small] [medium] [large] Puppies can become infected with hookworms and roundworms while they are still in the mother's uterus. The larvae (immature forms) of the worms migrate through the mother's uterus and into the developing fetus. Puppies and kittens can also be infected with roundworms and hookworms through their mother's milk. This is why it is so important to begin a deworming program when the puppies and kittens are 2 weeks old. < back to original page