We use TDI (Therapy Dogs International) and ATD ( Alliance Therapy Dogs)
We have used TDI since the implementation of the program about 20 years ago. We just started allowing ATD about 3 months ago. The training process and insurance are the biggest areas we look at. TDI has "uniforms" the owners/handlers wear khaki slacks and a white polo with the TDI logo. The dogs have identifying bandana's. ATD does not have specifics, so i was very clear with our standards of dress.
Let me know if you have any other questions.