Kennel Cough is caused by various micro organisms and infection can occur where there are lots of dogs together such as, at a show, boarding kennels or training grounds. It starts as a harsh scratchy cough combined with lung damage. Even though the dog may not appear to be too ill they still need to be treated by a vet. It is advisable to have your dog vaccinated at least four weeks before leaving it in a boarding kennel. The illness is transmitted through the breath.