Parvovirus-induced regression of canine transmissible venereal sarcoma

In 1981, during the worldwide canine parvovirus (PV) epizootic, canine transmissible venereal sarcomas growing in Beagles in a colony regressed earlier than expected after the dogs became infected with PV. Subsequent studies revealed that modified-live PV vaccine (feline panleukopenia virus) was capable of preventing tumor transplantation when the vaccine was inoculated simultaneously with the tumor in a site distant from the implantation site. However, the PV vaccine had no effect if it was inoculated 3 or 18 days after the tumor was transplanted.