Common respiratory diseases in poultry include Infectious Bronchitis Virus (IBV), Avian Influenza (AI), Newcastle Disease (ND), and Mycoplasmosis. These diseases can lead to severe respiratory distress, characterized by symptoms such as coughing, sneezing, nasal discharge, and lethargy. Infected birds often exhibit reduced feed intake, lower egg production, and poor weight gain, leading to economic losses for producers.