A. No loose stool and weight loss are not considered normal for any pet, nonetheless a puppy who is at risk for dehydration if this continues. I would recommend getting a second opinion perhaps, starting with a fecal examination to check for intestinal parasites and a Giardia test. Almost all puppy diarrhea's can be traced back to either parasites or dietary indiscretion (eating something they shouldn't have). Dietary indiscretion can also be caused by switching puppy's food drastically instead of doing a slow transition.
Also I would recommend maintaining puppy on a low fat diet such as Hill's I/D (can be prescribed by the vet) or Purina EN Gastrointestinal (OTC food). And to help prevent dehydration it is recommended to give puppies either Pedialyte over the counter or getting subcutaneous fluids through your vet.
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