Contagious and infectious diseases are those diseases of livestock that are caused by pathogens, such as fungi, bacteria and viruses. They can be transmitted from one animal to another, and can also spread from insects and vectors such as mosquitoes, ticks, midges, and flies. Some infectious diseases may also occur due to the consumption of contaminated water or feed, or exposure to micro-organisms in the environment. Some of the common infectious diseases in livestock include foot and mouth disease, blue tongue, black quarter, pox, Johne`s disease, bovine rhinotracheitis, and theileriosis. The measures to prevent infectious diseases in animals are divided into three categories, which include animal husbandry, biosecurity, and vaccinations. The adoption of good practices of animal husbandry involve providing clean water, clean housing, good quality feed, and isolating the sick animal. This book aims to shed light on some of the unexplored aspects of contagious and infectious diseases of livestock and the recent researches on them. Those with an interest in these diseases would find it helpful.