Kennel cough -- tracheobronchitis or Bordetella -- is an infectious and highly contagious respiratory disease that most dogs contract at least once in their life. Puppies are more susceptible to the disease because their immune systems are not developed; older dogs are also more susceptible than healthy adults, particularly as complications of aging compromise their immune systems.
Cause
Generally, dogs will pass kennel cough around when they have been boarded at the vet or a kennel. The disease is caused by a number of infectious pathogens, including Bordetella bronchiseptica, parainfluenza virus and mycoplasma, as well as canine herpesvirus, reovirus and canine adenovirus.
Vaccinations
A vaccination exists to ward off kennel cough, but it's generally good for just six months. If you let the vaccine lapse, your dog can contract the disease. Even if you keep the vaccine up-to-date, your dog can still contract kennel cough. If your dog is infected when he receives vaccine or if he has an antibody that works against the vaccine, he may still develop kennel cough.
Problems With the Vaccine
In some cases, the vaccine can fail -- if the vaccination is not stored corrected or if there was a problem in the manufacturing of the vaccine, for instance. Another reason a vaccine may fail in some cases is that it may not have the antigens to prevent a particular strain of the disease. Since kennel cough can be caused by a number of pathogens, one particular vaccine may not cover all strains or pathogens.