Service dog

n. dog especially trained to provide assistance to disabled people with every day tasks

A service dog is a type of assistance dog, specifically trained to help people who have disabilities other than visual or hearing impairment. Examples include psychiatric service dogs, mobility assistance dogs, and seizure response or medical response dogs. Service dogs are sometimes trained and bred by private organizations. In other cases, a disabled handler may train their own dog with or without the aid of a private dog trainer.
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A dog specially trained to assist a person that is physically or mentally challenged.