The parvo was first reported in North America and Europe in 1978 as epidemic causing gastro intestinal haemorrhaging in domestic dogs. As it is not reported in dogs or it is likely that it is mutant of cat virus or fox virus. The mutant means that the protein on the surface of virus has changed its shape. Therefore, the antibodies generated after vaccination do not neutralize the virus. Thus the vaccination fails and vaccination at 16 weeks is required. Further, the vaccinated mothers secrets antibodies, in its milk, that does no allow, the virus antigen to generate antibodies. However, now Intervet, company has come up with a vaccine that works and gives full protection, by vaccinating, at 10 weeks of age. The vaccination in dogs, should, not be done before eight weeks of age. Further, pregnant and bitches in heat, or thirty days within heat should not be vaccinated.