This collection features four peer-reviewed reviews on viral diseases affecting pigs. The first chapter summarises recent research on the causes and epidemiology of major bacteria, viruses and parasites found in pig production, focussing on those with a particular impact on safety and global production, such as African swine fever, Porcine Reproductive and Respiratory Syndrome (PRRS) and Porcine Epidemic Diarrhoea (PED). The second chapter reviews advances in understanding mechanisms of porcine viral disease transmission and pathogenesis. The chapter concludes with commonly used measures for prevention and control of viral diseases of pigs, emphasizing the importance of the vaccination programs as cornerstone of swine health programs. The third chapter discusses our current understanding of the mechanisms of resistance to the major respiratory diseases affecting pigs, including PRRS. The chapter considers the use of marker-selection and genetic modification as mechanisms to prevent the infection of PRRS and reduce its impact on swine health. The final chapter considers the transmission, clinical presentation, evolution and spread of two major diseases affecting swine production - PRRS and PED. The chapter reviews the impact of each virus on a global scale, as well as its impact on swine production in the United Kingdom.