Signs of illness in turkeys can vary depending on the underlying condition. Some common symptoms of a sick turkey include decreased appetite, lethargy, difficulty breathing, coughing, sneezing, diarrhea, abnormal droppings, swollen joints, lameness, weight loss, disheveled appearance, reduced egg production (in hens), and abnormal behaviors. If you notice any concerning symptoms, it is best to seek veterinary advice for proper diagnosis and treatment.