The following is from an article that appeared in the spring 1998 issue of Goat Tracks magazine. The following information from three separate scientific studies may help to clear up some of the mystery, but there are no absolute answers at this time.
More research needs to be done.
In early November 1995, bighorn sheep were heard coughing by the locals and hunters near Asotin, Washington. State wildlife agencies investigated and found a couple of dead sheep and a feral goat with the bighorn sheep herd. At the end of November, a bighorn ewe was found within 200m of the feral goat while a bighorn ram was next to the goat. The goat and ram appeared clinically healthy, the ewe had signs of respiratory distress. The animals were killed and sampled.