Wisconsin will require import permits for pigs entering the state starting March 1 to make sure the animals are free of a problem virus.
The virus is Porcine Reproductive and Respiratory Syndrome. Officials said it can cause reproductive failure in breeding stock and respiratory illness in young pigs.
Industry groups estimate the virus costs more than $600 million each year.
Pork producers and veterinarians disclose the PRRS status of pigs when acquiring the permit. They also must submit a certificate of veterinary inspection online.