This book is intended for diagnosticians and poultry veterinarians to aid in the identification and control of immunosuppressive diseases. The goal of this work is to present the reader with the most common diseases that can produce immunosuppression in poultry provide guidance for the diagnosis of immunosuppressive diseases and examine the challenges that a diagnostician may face in confirming a diagnosis of immunosuppression. It is the aim of the authors to also emphasize those areas that requ