The symptoms of parvovirus infection in dogs are: diarrhea, vomiting, loss of appetite, lack of energy, and in severe cases, blood in the stool in the later stages. Parvovirus is a viral disease that mostly occurs in puppies and adult dogs that have not been vaccinated. When owners find that their dogs have the above minor symptoms, they should promptly send their dogs to a nearby pet hospital for treatment. During the treatment period, they should not feed their dogs any food.