In my state I could put an ad in the paper and start teaching classes in my back yard or at a local park immediately. I might need a business license, but wouldn't be required to have a dog trainers license or provide any certification regarding my abilities or experience.

I'd love to know where to go to find a list of trainers that are actually licensed by their city, county or state. Not to run a business, but as licensed dog trainers. If there is such a thing it should be public information.