The disease is caused by parvovirus of types CPV-2, CPV-2a and CPV-2b. Infection is both serious and widespread in dogs. Signs, which include severe vomiting and diarrhea with blood, result from the virus damaging the gastrointestinal tract. The disease is spread via infected feces. Death in as early as 48 to 72 hours can occur in some dogs, although sudden death can also occur. Parvovirus infection may also cause bone marrow suppression and myocarditis (inflammation of the heart muscle). This virus is very resistant in the environment and is easily carried around on people’s shoes and other objects, leading to virus transfer. For this reason, even indoor hi-rise apartment dogs that never go out require protection. Vaccination is the most effective protective strategy for all dogs, young and old.
The above description is provided by the CVMA (Canadian Veterinary Medical Association)