There are 3 basic types of SD's (service dog's), Emotional (ESD), Psychiatric (PSD), and Mobility Service Dog (SD), according to several different SD groups. The emotional and psychiatric are very close to the same thing (mental) and can even overlap to mobility (physical).
Federal Law, is the The Americans with Disabilities Act, 1990, (ADA), defines
service animal as:
"any animal individually trained to do work or perform tasks for the benefit of a person with a disability."
The ADA defines a
disability as:
"a mental or physical condition which substantially limits a major life activity such as caring for one's self, performing manual tasks, walking, seeing, hearing, speaking, breathing, learning and working."
To be considered a service dog, the dog must be
trained to perform tasks directly related to the person's disability. What this means is that there is only ONE Service Animal group, not three.
Note: There are more self-trained SD's in the US, than those trained in a special school.
Any questions, I would be glad to answer either here or in private email.
My 'hobby' is matching disabled people with service animals.