Sadie, who was born with Down's syndrome, also has Type 1 diabetes. Hero's job is to alert her parents to any changes in her blood sugar levels, which he can do through his sense of smell.
To alert everyone to the situation Hero whines and will offer his left paw if Sadie's levels are too low, and if they're too high he'll give his right. Clever stuff, huh?
Sadie's parents keep a blog account of their little girl's journey through a Facebook page called Sadie's Hero. More recently the family has appeared on US television to tell one particularly amazing story about Sadie and Hero's touching relationship.
Her parents describe the day they realised Sadie and Hero's amazing bond - and that Hero had some seriously impressive skills. Sadie was at school over five miles away from their house, while Hero was at home with her mum Michelle Brooks when he sensed a change in her blood sugar levels.
'He's normally a very quiet dog. Whining is not in his protocol. But he just started whining and he would not stop,' mum Michelle explained on KUTV News. Because of the distance between Sadie and her pup, Michelle was unsure what do, but decided to call the school just in case.
'(Sadie's mum) called me and asked if I could check her numbers and they were fine,' teacher Ms Stoneman explained. 'I tested her and it was fine. Then within half an hour she went down.'
Hero's early detection of Sadie's levels could have potentially saved her life that day.
Hero's trainer KC Owens said, 'I can't explain it.'
'I think it's like mother's intuition. These dogs have abilities and senses beyond our understanding.'
This isn't the first time we've heard about these amazing sense dogs, either. Earlier this year a little boy with diabetes was saved by his dog in the middle of the night.
After the hugely positive response Sadie's mum took to Facebook to praise the family's dog for his life-saving skills, saying, 'While we can't and won't even try to explain how this happens, we feel blessed. Even without the long distance alerts, he is amazing!'