In mild cases, dogs will be alert and continue to eat normally. In more severe cases, a dog can become feverish, depressed, lethargic, expel a thick yellow or green nasal discharge, and possibly even develop pneumonia. Some very severe cases are fatal.
If you suspect your dog has kennel cough, isolate the affected animal from all other dogs, and contact your veterinarian immediately! Kennel cough spreads easily and quickly from dog-to-dog through the air. Keep all food and water bowls, and toys separated. Additionally, some pathogens that cause kennel cough can be transmitted from dog to dog via fomites (clothes, shoes, etc.). If you think one of your dogs has kennel cough, wash yourself and your clothes, and disinfect your shoes before you come into contact with your healthy dogs.