This book includes thoroughly revised and reviewed information with content of the most important diseases throughout the world. It presents up-to-date information on diseases effecting ruminants as Fasciolosis, Freemartism and BVD, as well as, present important information about behaviour and evolutionary and morphological anatomy. Included also are observations collected during experiments using immunohistochemistry, flow cytometry and scanning and transmission electron microscopy. This book was written by some of the best researchers in each area, from universities located in Spain, Portugal, US, Switzerland, Brazil, Italy and Slovakia. Completely revised chapters reflect the information from current literature.