If you are sure it is getting enough nursing time in, ask your vet the question. If it is Too much, animals get diabetes, but this would be unusual. Maybe some other health issue? Did someone drop the pup? Bump it's head? Does the pup respond to stimuli? Noise, tickling the feet pads?
I'm not sure anybody has ever evaluated that! They pretty much just eat and sleep at that age and it seems sometimes they're eating and sleeping at the same time! Are you asking because the pup is crying a lot? If that's the case maybe it's not getting enough to eat.
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