The dog Ethan was identified by a microchip in his neck, and was discovered after a man walking on a lakeside pedestrian path saw the ground moving and dug him up.
Firefighters then took the mud-covered terrier to a local vet who nursed him back to health.
Sabrina Zamora, president of an animal association in Charleville-Mezieres, said Ethan was as "flat as a pancake" when he was dug up from his grave on Tuesday.
Ethan was "completely cold" and "barely breathing" when he was taken to the vets.
His veins had collapsed due to the cold, so veterinarian Philippe Michon used hot water bottles to warm him up and the black and white terrier was back on his feet after just 24 hours.
"It's extraordinary, we only see this in TV movies," he said.
"He came back to life and without a scratch. It's rather miraculous."
The poisoning had caused Ethan to experience convulsions which is why the passerby saw the ground moving.
"[Ethan] had an unbelievable chain of luck," Michon said. "If the ground hadn't trembled, no-one would have taken a shovel to it."
Police are now investigating claims that Ethan's owners gave him away.
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