When will the USDA allow testing for Mad Cow Disease? Until the US Gov't allows testing of cattle for Mad Cow Disease there will always be a growing concern. A person eating beef cannot tell if it contains the prion and it generally takes years for symptoms of the disease to manifest itself. Like Kuru in humans (eating human parts), the problem comes about by the feeding of cattle parts (bone meal, etc.) back to cattle which is still a prevelant practice. It is natures way of saying, "you better not do this". Signed: DVM