A. I would definitely let the breeder know about this situation. A reputable breeder practices good deworming techniques - administering medications to the mom as well as all of the puppies (at least 2 or 3 times). However even this may not prevent infestation completely, and there's no way to prove that your dog hasn't contracted roundworms since you brought her home from the breeder, so be prepared for possible indifference or denial on the part of your breeder.
A. roundworms are extremely common, many puppies are either born with it or get it through their mother's milk right after birth. Although roundworms are extremely unpleasant they are rarely a danger to the dog's life. Breeders are well aware of the roundworm problem, some of them treat their dogs better than others but they all know the risk.
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