Can a snake be a legitimate service pet?
http://www.cnn.com/2015/08/15/us/restaurant-snake/...
A man and woman in Missouri went to a restaurant accompanied by a snake. When customers complained to the manager, the manger confronted the man, his date, and his snake.
"He said ... it's my service animal. And I'm allowed to have it because it helps me with my depression,"
A line in the article answers the question in this thread's title: "The American with Disabilities Act states "only dogs are recognized as service animals."
However, the manager at the restaurant didn't know that and apparently allowed the couple and their snake to stay and complete their meal.