What is the best dog for a boy with ADHD?

The best breeds are those that have a calming effect such as Labrador Retrievers and St. Bernards. They tend to be a little laid-back and you may want a more active dog. It's probably best to check out your local shelter and consider adopting an adult dog whose personality has already been assessed and who may be trained. A puppy may be a bit much to handle. Small breeds tend to be excitable and yappy. You must also be willing to assume  a lot of the responsibility for care of the dog.