I found this online:
Basic home treatment for kennel cough includes:
Home Vaporizing Treatment
- Keeping your dog warm, quiet and free from drafts
- Removing your dog's collar to prevent excessive coughing stimulation
- Encouraging your dog to drink plenty of fresh water
- Providing wet food just in case your dog's throat is sore and irritated
You can provide additional relief for your pet by giving him a vaporizing treatment three times a day. Run a hot shower in your bathroom and let the steam build up with the door closed. Take your dog into the bathroom and let him breathe in the steam for 20 minutes. The vapor will help open his bronchial tubes, which in turn makes his coughs more productive. This will enable your dog to rid himself of more of the phlegm clogging his airways.