Service Dog: Medical Alert Dogs (MADs)
Job: To alert their handler to dangerous physiological changes such as blood pressure, hormone levels or another verifiable, measurable bodily symptom.
Handler: May or may not show signs of disability.
Gear: Depending on the handler’s disability, the dog may or may not have specialized gear.
Notes: Medical Alert Dogs’ jobs and functions can vary widely. Also, all DADs are Medical Alert Dogs, but not all Medical Alert Dogs are DADs.
excerpt taken from http://www.anythingpawsable.com/types-of-service-dogs