Parvovirus typically affects a dog's intestinal tract, often infecting dogs less than a year old. This virus has a long life and is highly resistant to many disinfectants, so it's found just about anywhere that's seen a dog. Some dogs are considered subclinically infected, carrying the virus without appearing sick.
Whole Dog Journal reports veterinary experts believe most dogs have been exposed to parvovirus. About three days after being exposed to parvovirus, a dog begins to shed the virus, often before he exhibits symptoms. An infected dog will shed the virus in his feces for up to 10 days. The virus can be virtually anywhere because it can be transmitted on other animals, clothes, shoes, food bowls and other inanimate objects and can live for months. A dog can carry the parvovirus without showing obvious symptoms; however, if he carries the virus, he's been infected with it. Symptoms of parvo infection include severe vomiting, lethargy, lack of appetite and foul-smelling diarrhea that can dangerously dehydrate a dog. An infected dog requires aggressive treatment at the vet's office, where he'll receive a variety of medication, intravenous fluids and supportive care. Since the virus is pervasive and potentially lethal, the ASPCA recommends vaccinating all dogs for parvovirus.