You 'know' me well enough to know that I'm not one from shying away from the vets but I need to tell of a tried and tested home remedy for kennel cough (disclaimer - as long as you KNOW it's kennel cough).
Liquorice root (sticks).
You can buy it from good health food stores here so I assume you can overseas too.
You boil a kettle of water and pour into dogs water bowl. When the water is still hot, add one spoon of honey (which helps coughs anyway, plus is disguises the rather strange liquorice taste), stir it round and then add one stick. Leave to infuse until the water is cold enough for dogs to drink and then fish the stick out.
Once that bowl is down for the dog(s) to drink, get another batch on the go. I actually used a stick twice and then threw it away and started over with a new stick.
I did the above for about a week.
The two dogs of ours who had KC recovered without any medication and none of the other dogs got the KC.
I've shared this with many people over the years (funnily enough though, this is the first time I've seen the topic come up here) and virtually everyone has had the same success with it.
Disclaimer - any young pup, elderly dog or otherwise unwell dog must see a vet.
Oh I need to add another bit
When our dogs had KC, they had not been in direct contact with any dog who had been coughing. However, *I* had and I firmly believe that I carried the virus home on my clothing and it was dead on ten days later when my dogs started to show symptoms.