Sharky,
Yes! DOs can practice in Peru. I travel to Peru on mission trips every summer, and I have met a few DOs along the way. Here is a link to an article about Dr. Maggie Byers, D.O. who established a clinic in Peru: http://www.dioceseoflansing.org/index.cfm/NewsItem?partnerarticle=1&id=147&From=Home I hope this helps answer your question.