A postal worker in St. Louis called Stray Rescue after finding the dog collapsed on the ground.
Rescuers said she wasn't moving when they got to her.
"Just the panic in the caller's voice," Dr. Sarah Frei with Stray Rescue St. Louis, told KTVI. "We knew that it was going to be a life-or-death situation and that minutes counted."
The veterinarian said her body temperature was so low a thermometer couldn't even read it.
RELATED: Veterinarians bring nearly frozen, unresponsive cat back to life
Even though the dog was in a coma, she is slowly making strides with constant care.
Officials are not sure how the dog got outside.
Pet owners are reminded to give their pets extra care during the colder months.
RELATED: Your dog's fur coat might not necessarily keep him warm this winter
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