Service dogs

A service dog is a type of assistance dog specifically trained to help people who have disabilities, such as visual impairment, hearing impairments, mental illnesses (such as posttraumatic stress disorder (PTSD)), seizure disorder, mobility impairment, and diabetes.

Desirable character traits in service animals typically include good temperament or psychological make-up (including biddability and trainability) and good health (including physical structure and stamina). Some service dogs are bred and trained by service dog organizations, while others are bred by breeders, and trained by private trainers or even the individuals with disabilities who will someday become their partners. Labrador Retrievers, Golden Retrievers, Labrador Retriever/Golden Retriever crossbred dogs, and German Shepherd Dogs are among the most common dog breeds working as service dogs today in the United States. Although dogs of almost any breed or mix of breeds may be capable of becoming a service dog, very few dogs have the requisite health and temperament qualities. Such a dog may be called a "service dog" or an "assistance dog", the terminology typically varying by country or region. The term "seeing eye dog" is frequently used as a generic label referring to any dog assisting individuals who are blind or with visual impairments.

During the First World War, the German army relied heavily on the use of German shepherds as ambulance and messenger dogs. The school helped to train the German Shepherds to serve as guides. Dr. Gerhard, from Germany, opened the world’s first guide dog school in 1916. Over the courses of both world wars, World War II helped lead to a major increase in the number of guide dog schools in the United States. The guide dogs that were used by veterans in the United States are linked to the original training schools set up in Germany to care for World War I veterans.

...
Wikipedia