I think the puppy triggers her mothering instincts. She wants to either wash the puppy or feed it, both of which stimuli make her salivate. So long as there is no aggression from her I would not worry. As the pup matures she will get over it.
Dogs also dribble if they become over anxious. If she is troubled by the puppy and anxious a course of tranquilisers from the vet may help to calm her down.
Dogs also dribble if they become over anxious. If she is troubled by the puppy and anxious a course of tranquilisers from the vet may help to calm her down.