Cancer poses a serious threat to wild animals, say twp pathologists working for the Wildlife Conservation Society, the second leading cause of death, as in humans.

Understanding the cancers in animals will help understand them better in humans. The pathologists list 22 species that suffer from viral cancers. While some of the viruses have only been found in wildlife, others are closely related to human viruses, including papilloma virus, herpes simplex virus and hepatitis virus.