The USDA-APHIS released its 2012 Foreign Substance test results on April 12, 2013. In total the USDA took 478 samples from 24 sanctioned shows of which 309 samples were positive. The USDA has a zero tolerance policy for any substance other than the three permitted substances in the HPA.
Other independent equine testing authorities do not employ zero tolerance policies for all substances, citing many factors including normal equine veterinarian practice and environmental factors to name a couple.
Click here to view the results from the USDA testing in 2012.