The Denver Post reports that horses and one cow have tested positive for Vesicular Stomatitis, known as VS.
Authorities say that over the last two weeks, the office has been receiving about 10 reports daily of animals showing symptoms of VS. The disease causes painful, blister-like lesions on horses, cattle and pigs.
The virus is spread by insects and from animal to animal through open sores and saliva.
The quarantines are located in Adams, Boulder, Douglas, El Paso, Larimer, and Weld counties. A cow in Weld County has tested positive for the disease.
The State Veterinarian's Office says it is not recommending that livestock shows be canceled.