Primary ciliary dyskinesia (PCD) is an inherited disorder of the cilia affecting Old English Sheepdogs. Cilia are microscopic, hair-like structures that line the nasal cavity, trachea, and bronchi of the respiratory system, the fluid filled cavities of the brain and portions of the reproductive tract. Normal cilia move in wave-like patterns to aid the movement of fluids in the brain and reproductive tracts and prevent large particles and pathogens from getting into the lungs. In PCD, affected dogs have cilia that are either malformed or do not move. Particles and pathogens cannot be removed from the upper respiratory tract and can lead to sinusitis, bronchitis and pneumonia. Affected dogs typically present a few days after birth with respiratory disease. Symptoms include coughing, sneezing, nasal discharge and frequent respiratory infections. This disorder also causes immobility of sperm, therefore affected male dogs are sterile. Dogs with PCD may also have a transposition of organs in the thoracic and/or abdominal cavities, resulting in a mirror image of the normal placement of the heart and lungs and sometimes other organs. This transposition is called situs inversus and does not usually cause clinical problems. Dogs with this disorder can live for years if their chronic respiratory infections are managed.