Parvovirus is a serious viral disease; it can be fatal when its symptoms go untreated. In addition to lethargy and depression, parvovirus can cause severe vomiting and diarrhea, which can cause your dog to dehydrate quickly. Getting your dog to a veterinary hospital when you notice these symptoms is the key to successful treatment. He'll stay there for several days while he recovers and rehydrates.
The Disease's Duration
According to the ASPCA, this virus can't be killed, it can only be treated. Treatment typically consists of a hospital stay, during which your dog will receive antibiotics and medication to keep his vomiting under control. Because dehydration is a serious concern, your dog will also be given IV fluids. The duration of your dog's treatment depends on the severity of his symptoms, but the typical length of a hospital stay is between 3 and 7 days -- he won't be discharged until the parvo symptoms have disappeared.