In the past few years, diseases in sheep have grabbed the headlines several times. The repercussions of a disease range from a sheep slaughter to an impediment in livestock yield. Some diseases are zoonotic diseases that can be passed from sheep to humans. Considering the major consequences of the diseases in sheep, several biologists are working towards providing an early warning system for sheep producers. Many diseases can be prevented through the proper control strategy or vet consultancy, if applied in a timely manner. However, to evaluate the symptoms of a disease, it is critical to be well versed with it. Therefore, in this book, efforts have been done to assemble a wide range of published research studies under this central theme.The first Chapter reports the colonization of the placenta without congenital malformations in sheep infected with Schmallenberg virus (SBV). The second Chapter describes the presence of antibodies against Akabane virus (AKAV) in ruminants in Nigeria. AKAV is a pathogen responsible for abortions and congenital malformations in ruminants. Chapter 3 accounts the popularity of Haemonchus contortus, a blood sucking parasite causing anemia, in slaughtered sheep in Iran. The characterization of one Chinese sheep Border disease virus (BDV) and the complete coding sequence of BDV strain JSLS12-01 are described in Chapters 4 and 5, respectively. Chapter 6 features the seroprevalence rates of Bluetongue disease in sheep in many areas of Iran. Brucellosis, world's major zoonosis, leads to abortion, infertility, and low milk yield. This disease has been reviewed in Chapter 7. Congenital disorders in sheep are discussed in the following two Chapters.Cryptosporidiosis is a zoonotic disease affecting human populations and domestic animal. Its prevalence in small ruminants in Mexico is discussed in Chapter 10. The gastrointestinal tract disorders in sheep are presented in the following two Chapters. Leptospirosis infection in sheep flocks in Southeast Brazil is described in Chapter 13. The prevalence of Lungworm infection in small ruminants in Southern Ethiopia is reported in Chapter 14. The bacteria and the characteristics of Mastitis in sheep are illustrated in Chapter 15. Nairobi sheep disease virus and the major cytokine responses in infected sheep are discussed in Chapter 16. Paresis and paralysis in sheep are described in Chapter 17. The transmission of bronchopneumonia infection from one infected animal to all sheep is talked about in Chapter 18. The epidemiological pattern of Q fever in domestic ruminants in described in Chapter 19. Retroviral infections and inherited Rickets in sheep are explained in Chapters 20 and 21, respectively. The evaluation of the haplotypes distribution in ancient sheep and the modern population is accounted in the following Chapter. The characterization of the orf virus and the spider lamb syndrome in sheep are discussed in Chapters 23 and 24, respectively.This book will be beneficial for students, researchers, teachers, and sheep producers.