farmyard pox farmyard pox farmyard pox is a group of closely related parapoxviruses of sheep and cattle that can cause bovine papular stomatitis, orf and milker's nodule in humans. farmyard poxorf - a type of farmyard pox (thumb with two denuded orf lesions, following a bite by a sheep)specialtyinfectious diseasestypesbovine papular stomatitis, orf, milker's nodule