Christi Smith had taken in a foster pit bull for less than a week when the dog came to the rescue of her 4-year-old son, saving him from a life-threatening health scare.

Smith, 28, of Brooklyn Park, Minn. says everything was normal the night of Oct. 2 when she put her son, Peyton Anderson, to bed.

Peyton woke up a few hours later to get a glass of water and TaterTot, the 10-month-old pit bull, began acting strangely.

"TaterTot was whining and barking," Smith, 28, told Goodmorningamerica.com. "I didn't think anything of it and just tried to get everyone to go back to bed."

Around 1 a.m. that same night, Smith was awoken again, this time by TaterTot, who was running between Smith's and Peyton's bedrooms and barking.

"I got up and went to check on my son and TaterTot was on the bed, trying to shake his bed, wake him up and lick his face," Smith said. "At that point my son was barely breathing."

Smith drove Peyton to the emergency room where he was diagnosed with low blood sugar. Doctors, who say the boy is not diabetic, have not been able to determine what caused Peyton's sugar to drop so dangerously low, but told Smith the dog likely detected Peyton's ketones, a sign the body is burning fat for energy instead of using glucose.

"A lot of people are saying it could be because he was producing ketones and that TaterTot picked up on it and that's why he started acting funny," Smith said. "He could sense something was wrong."

Smith had originally agreed only to foster TaterTot after he spent more than a month in and out of foster homes in the Minneapolis area. Now, Smith says, the dog is a permanent member of their family.

"Absolutely," she said. "Pit bulls just have a bad reputation, but they're actually great family dogs. They're really friendly.

"TaterTot and Peyton pretty much have been inseparable since the day that we got him."