A terrier who was burned with boiling water and thrown off a building in China has made a strong recovery thanks to a passer-by who spotted him.

Tuffy, so named because he had to be so "tough", was attacked by his owner and dropped off a four-storey building after chewing his phone, Animals Asia reported.

He was spotted by Yan Yingying, who was appalled at the cruelty the six-week year old puppy had endured and paid for his recovery treatment.

She is now Tuffy's owner, and has nursed the animal back to full health in what the vet has described as a "miracle" recovery.

Animals are not meant to be able to survive with more than 50 per cent burns covering the body, but Tuffy had 60 per cent (YouTube, Animals Asia)

Emily Drayton, an Animals Asia vet, said she was sickened to see the dog when it was passed into her expertise.

"I was shocked and sickened to my core. I could not stop the tears fro rising, there was no point," she said in a press statement.

"Never had I seen an animal in so much pain."

Tuffy required round-the-clock care of injections and painkillers for the burns covering 60 per cent of his body before he was better again.

When he was first found, he was unable to close his eyes because the scalding had caused his skin to tighten so badly.

Dr Drayton said many people would have walked past the animal where Ms Yan stopped to rescue him.

"The sight must have been so horrific, and I'm sure many people would have walked past and pretended not to see.

The six-week-old's skin was so badly burnt he could not shut his eyes to sleep (YouTube, Animals Asia)

"But she took Tuffy to a local vet and paid for all his veterinary care."

Jill Robinson, founder of Animal Asia, said the dog's recovery was a "miracle".

"Tuffy has more passion for life than any animal, or person, I have ever met," she said.

Animals Asia is best known for rescuing bears from the bear bile trade.