Service dogs are typically specifically selected dogs that are highly trained to preform tasks and assistance to a person with disabilities. 

A person with a disability is defined under the Americans with Disabilities Act (ADA), a person with a disability is defined as someone who has a physical or mental impairment that substantially limits one or more major life activities, has a record of such an impairment, or is regarded by others as having one. 

Service dogs are trained to work for a single person. This is not the same thing as a Theropy Dog or an Emotional Support Animal (ESA). Again qualified service dogs are highly trained, ESAs require no training and do thier work "naturally" by just excisting around their human companion. 

Service dogs don't actually start working until the age of 2 or older. Before this age they should be receiving the necessary education to be a Canine Good Citizen, Pet Dog Ambassador, or other wise a super star in their manners. 

Service Dog candidates are none-reactive, confident, food motivated, attentive to their handler, and are generally calm, controlled, and attentive to their handler in a varity of environments and with many distractions. Typically we describe a good service dog as unflappable. 

If your dog isn't quite to this point that's okay they may still be able to provide assistance in more restricted settings, such as an At-Home-Only Service Dog. 

Should you want to work towards training a dog you already have to become a service dog they need to be able to pass the Canine Good Citizen or Pet Dog Ambassador tests first so this will be your top priorety. 

While it's not required we recomend that you and your dog acheeve your Pet Dog Ambassador certificate. This is a beutifully designed program