Max was being walked by his owner, Jessie Streich-Kest, and her friend, Jacob Vogelman, in Brooklyn's Ditmas Park Monday night, when a giant tree fell on them.
It was 12 hours later before their bodies were discovered, along with Max who had sustained life-threatening head injuries.
"It's just a testament to Max's spirit that he pulled through this tragedy," veterinarian Brett Levitzke, who is treating the dog, told ABC.
"It's also a testament to his owner that she went to a local shelter and saved putting him to sleep," he said. "That's why the whole story is really heartbreaking, but hopefully it will have a happy ending for Max."
Max had been adopted from an ASPCA shelter by Streich-Kest, a special education teacher, two years ago when she first moved to Brooklyn.
"They were inseparable," a friend said.
Max still needs surgery but is slowing improving and is welcome to stay with them at Verg South as long as necessary, said Dr. Levitzke.
He'll then go to live with Jessie's parents.