Assistance dogs is the universal term that refers to dogs uniquely trained to assist individuals with disabilities to lead a more independent life, including Guide dogs for the blind and visually impaired, Hearing/Signal Dogs for the deaf and hard of hearing, and Service Dogs for those with disabilities other than vision and hearing.  Additionally, Facility/Therapy Dogs work with professionals in facilities & organizations where interaction with a dog is beneficial to the healing process  - each of these astonishing skill-sets is the result of lengthy, loving, & committed training.  Among these three main groups, there are many distinct specialties of skill sets, and organizations like PWP will often specialize in a few specific types.  Examples include Balance Dogs and Seizure Dogs  Additionally, there are varying types of certifications for Assistance Dogs.