Parvoviruses are single stranded nonenveloped DNA viruses. Multiple species of parvoviruses in rats include Rat Virus (RV or Kilham rat virus), H-1 (Toolan’s H-1 virus), Rat Minute Virus (RMV 1a, 1b and 1c) and Rat Parvovirus 1 and 2 (RPV-1, RPV-2). Of these, RV is the only virus species reported to cause clinical disease in rats. Clinical disease from RV has been reported when virus was introduced to a naive population. In newly infected breeding colonies, RV may cause decreased fertility, small litters, fetal resorption, and runting of pups. RV infection in juvenile and young adult male rats may result in lethal disease from hemorrhage and necrosis of brain and gonads.