Updated and Revised. Canine parvovirus, "parvo," is a viral disease that is common in puppies under six months old. Parvovirus is a kind of virus that has many types. Each type normally affects specific species such as dogs, cats, or humans. Today, canine parvovirus is one of the most widespread diseases found in dogs. If the disease is not diagnosed early enough, it can cause death. If it's diagnosed early and an aggressive therapy is used for treatment, your dog can be saved.