A chicken is regarded to be in a state of good health when all of its body organs and systems are normal and perfectly functioning. Any alteration in the state of its body, or of any of its organs, which interferes with the proper performance of its function(s) is what is regarded as a disease. Naturally, chickens are flock animals, therefore, have the potential to spread very fast any contaminated disease amongst them. While on the contrary, it is a dream of every chicken keeper to want to raise healthy and disease free flock. The benefits of doing so can never be over emphasized. Some of the invaluable topics covered herein include: Signs exhibited by sick chickens. Stress in chickens (Causes and Control). Vices in Chickens (Causes and Control). Predisposing factors to chicken diseases. The most common chicken diseases (symptoms, causes, preventions and treatments). How to effectively deal with pests and diseases affecting chickens.