Few days ago, the boy's mother, Christi Smith, from Minnesota, had rescued the pit bull just hours before being put down by a local animal shelter.
Smith planned to foster the 10-month-old canine, called Tater Tot, until she could find him a permanent home.
The pooch may be on its way to become part of the family now after he saved her son's life last week by alerting Smith that the boy was not well in the middle of the night.
"He just seemed kind of weird. He wasn't really coherent - deliriously tired," Smith said.
Although the dog had only been in her home for a few days, the canine quickly sensed something was wrong and began licking and jumping on the boy when he wouldn't wake up.
"He kept on whining and barking and running between the two of us," Smith told Fox 9 News.
When she checked on her son she found that he was barely breathing. The boy was rushed to the emergency room where doctors found his blood sugar to be dangerously low.
"If his blood sugar was that low, he may have been producing ketones. That may have been what the dog picked up on," said Isis Sanchez, of Blue Pearl Veterinary Clinic.
Sanchez said Tater Tot's keen sense of smell likely helped him realise the change in the boy's body.