Legally, pet food manufacturers can make the “made in the U.S.A.” claim as long as the product was assembled in this country – even if the ingredients are imported. So when you’re shopping for safe treats, it’s not enough that a product claims to be made in the U.S. You want to be sure all the ingredients originated here as well.
The U.S. certainly produces its own share of tainted products, but as a general rule, the contaminating agent is quickly identified and these days, immediate action is taken to remove the product from store shelves.

The chicken jerky dog treats and other treats suspected of causing illness and death in so many pets have ingredients imported from China. Despite the efforts of the FDA and independent laboratories to isolate the contaminant, nothing has been identified, and five years after the first reports of sick and dying pets, the treats are still being produced by major pet food companies and sold by major retailers. So I would certainly strongly recommend avoiding any product containing ingredients sourced from China.
That said, I have found several excellent quality treats from New Zealand and Canada. The important point is to know and trust your treat company’s commitment to purity and quality control.