Seeing eye dogs

Today I had to laugh at Zack and Seth. Seth was playing a plug in football game. Zack was giving him the play by play action (or rather READING to him what the words on the screen said). As Zack would walk away, Seth would yell for him to come back. "I can't see Zack!" Zack would come back settle in at Seth's side and read, the by lines, the yardage...whatever. Which made me think of a "seeing eye dog".