South Dakota's Animal Industry Board says two cases of vesicular stomatitis virus have been confirmed in livestock in the western part of the state.
The highly contagious animal disease is transmitted by flies and midges. It can infect horses, cattle, sheep, goats and pigs. It's rarely fatal.
There also have been cases this year in Colorado, New Mexico, Texas, Utah, Wyoming and Arizona.
South Dakota State Veterinarian Dustin Oedekoven says good sanitation and biosecurity measures can help prevent the spread of the disease.