Diseases may affect swine health and production in multiple ways. While the impact of some diseases is quite evident, such as abortion or death, the effects of other diseases are more subtle, such as reducing appetite. A reduced appetite may be difficult to observe but in turn will reduce the conversion rates of feed into weight, increasing the time it takes to bring a fat hog to marketing. The effect of some diseases is even more complex. For example, for a number of diseases, countries have agreed to impose specific restrictions to products coming from regions affected by those diseases. Thanks to the efforts of producers, practitioners, and government officers over decades, the U.S. is free from the most important diseases that cause an impact to trade. Taking advantage of such a privileged situation, approximately 25% of U.S. pork production is exported.
