A viral infection of cattle caused by a parapoxvirus (viruses of ungulates), producing lesions similar to those of cowpox and infectious ecthyma (ulcerative pyoderma) on the udders and teats of cows and on the oral mucosa of suckling calves.

It begins as small red papules that evolve to vesicles, pustules, and scabbing. It may be transmitted to humans during milking, producing milker's nodules; and there may then be retransmission to uninfected cows.