Kennel Cough is a common upper respiratory disease in dogs caused by one or
  more airborne infectious agents that irritate the interior of your dog’s
throat.  Symptoms will usually show themselves within three to seven days after
the  initial exposure and last about ten days to three weeks. Your dog can then
  continue to carry the offending bacteria or virus for up to fourteen weeks,
  making him contagious to other dogs even after he is completely recovered.

The disease causing agents are airborne, but your dog needs
  relatively close contact with an infected dog or an item that an infected dog
  has had contact with, like a toy or water bowl. The disease does not survive
  long outside of the body.

 The most notable symptom that also gives the disease its common name is
  coughing. Infected dogs will develop a cough with a dry hacking sound. The coughing usually goes on every few minutes all day long and is sometimes accompanied by gagging, sneezing or a watery discharge from the nose. Canine cough can progress to more severe symptoms in dogs whose immune systems are not working as they should be or are compromised by other ailments, or in unvaccinated puppies. Some of these might include lack of appetite, listlessness, fever, and pneumonia.

 Treatment of kennel cough depends on the severity of the
  symptoms. In an  otherwise healthy and alert dog, medication is often not required and the
  disease is allowed to run its course. Antibiotics can be prescribed if there is
  a possibility of complications from secondary infections, but this does not
  necessarily lessen the amount of time that your dog is ill or contagious.
  Over-the-counter or prescription cough suppressants may also be utilized to
  lessen the severity of the cough and to make your dog more comfortable. 
Vigorous play or exercise will  make your dog breathe harder, which further irritates his throat and encourages  more coughing. A dog that has already had canine cough is
usually more resistant  to contracting it again.

To help prevent Kennel cough....Vaccinate, vaccinate, vaccinate. The standard five-way vaccination, DHLPP, will provide protection against one of the most common infecting agents of the disease, parainfluenza. An intranasal vaccine specifically for canine cough is
  also available that goes directly to the area that needs the most safeguarding:
  the nasal passage and throat since this is how the disease enters the body.
Some  dogs will display mild signs of canine cough after receiving the
vaccination,  but these will typically subside within a few days.