Dear readers... This book provides readers with information on everything from classical to modern veterinary medicine research. Emphasis will be placed on the area of Veterinary Parasitology. By reading this book, we will be able to improve our knowledge and keep up to date with certain zoonoses. This knowledge of the main agents with zoonotic potential should be seen as essential for the public health of the population. Thus, Veterinary Medicine, through research and extension work, contributes to elucidating and, above all, providing information on various parasitoses, as we will see here about nematodes, cestodes and trematodes. In this context, we would like to thank everyone involved in this work, especially the Veterinary Parasitology Research Group at the Federal University of Tocantins, the National Council for Scientific and Technological Development (CNPq), an agency of the Ministry of Science, Technology, Innovation and Communications (MCTIC), for promoting research in our country and our collaborators from partner companies. I wish you good studies and great learning.