Kennel cough, also known as infectious tracheobronchitis, is a highly contagious respiratory disease of dogs. In most cases the disease occurs when a dog becomes infected with one, or more, of the following viruses: canine adenovirus 2, canine distemper virus, and canine parainfluenza virus. The Bordetella bacteria may also cause kennel cough, and in some cases it also occurs as a secondary infection that develops when a dog has been infected with a viral respiratory infection.