A deadly virus is spreading among horses in the western United States and parts of Canada. The highly contagious Equine Herpes Virus-1 isn't a threat to humans. But it spreads easily among horses and even llamas and alpacas. So far, it's caused scores of horse owners to quarantine their animals. And as KUNC's Kirk Siegler reports, it's also forced the cancellations of horse shows and competitions in Colorado and other states.