Research designed to improve genetic resistance to diseases in farm animals has been conducted for a long time and is justified for both animal welfare and economic reasons. Approximately ten years ago the costs of disease to animal production were estimated at between 10% and 20% of total production values. These costs almost certainly have not been reduced during the last decade. Breeding programmes which improve disease resistance may therefore contribute to significant increases in production yields.

This special issue of the Review gives an overview of the many defence mechanisms and genetically variable susceptibility or resistance loci in domestic animals. In addition to these general aspects of resistance genetics of the host, this book is devoted to the disease-causing infectious agents (parasites, bacteria, viruses, etc.) and highlights the different pathogenic characteristics of a given species in relation to resistance mechanisms.

Finally, this issue of the Review also sheds light on the three main strategies for the improvement of disease resistance traits in domestic animals, namely: conventional breeding programmes based on morphological traits; marker-assisted selection utilising associated DNA polymorphisms; and transgenic approaches.

This book offers a total of twenty-seven papers by fifty-nine authors and co-authors recognised internationally for their expertise in this field.