Check the credentials of the service providers to know if they have had experiences that are related to dog training Washington DC. This means that he must have handled the same kind of animals before. The professional must have website. With a lot of companies advertising their businesses on the web, it is not far that the professional himself has also a website in order to promote his service.
He needs to have some background on the service that he is currently offering the public with. Without experience, it would be hard to trust the professional to do good on the service. That is why he needs to have some experience first before he can be called an expert in this service.