Dog saves life of sleeping boy

[skb]

CBS News reports that a dog saved the life of a little T1 boy by waking up the mother. You can read the story here. http://www.cbsnews.com/news/dog-saves-the-life-of-sleeping-boy-with-type-1-diabetes/. 

Is 57 mg/dl really life threatening or was the dog able to sense that it would go lower ? 

[Shanny]

I wondered that too . . . or could sense that it was dropping rapidly.

[Shalynne]

Acute sense of smell, most likely.  The dog could probably sense changes in the boy's scent, and that the changes were rapid.