The USDA already oversees a CWD monitoring and herd-certification program. That said, it's both difficult and expensive to reliably test live deer for CWD, according to the National Wildlife Health Center. Tissue samples are typically taken from deceased animals to make a positive diagnosis. It is therefore possible to ship infected animals that may appear healthy to disease-free states like Indiana. The roughly 10,000 deer and elk farmers in the U.S. are currently shipping cervids between states at an unprecedented rate. Despite this uptick, at least 21 states already prohibit breeders from importing certain captive deer species.