Bovine papillomaviruses (BPV) are a paraphyletic group of DNA viruses of the subfamily of Papillomaviridae that are common in cattle. All BPVs have a circular double-stranded DNA genome. Infection causes warts (papillomas and fibropapillomas) of the skin and alimentary tract, and more rarely cancers of the alimentary tract and urinary bladder. They are also thought to cause the skin tumour equine sarcoid in horses and donkeys. BPVs have been used as a model for studying papillomavirus molecular biology and for dissecting the mechanisms by which this group of viruses cause cancer.