Parvoviruses are small, single-stranded DNA viruses that primarily infect animals. They are known for their ability to replicate only in rapidly dividing cells, which is why they often target tissues like the bone marrow and intestines. In dogs, the most well-known parvovirus is canine parvovirus, which can cause severe gastrointestinal disease. In addition to affecting dogs, parvoviruses can also infect other species, including cats and humans. In humans, human parvovirus B19 is known to cause a mild illness called fifth disease, characterized by a distinctive rash. Overall, parvoviruses are significant in veterinary and human medicine due to their impact on health.