Being a stray dog is a hard and often tragic life. With no one to care for them, many homeless dogs suffer from exposure, hunger, and untreated medical issues.

Some cities have more strays than others, and in Mexico City, there are over a million stray dogs wandering the streets, looking to survive. And for one of them back in early 2015, the odds of survival were not good.

This dog was in so much trouble that one passerby was compelled to scoop the dog up right then and there and get him some help. The poor dog’s whole body was covered in cancerous tumors, many of which were also open and infected.

He was also severely malnourished. And people had been walking right by him all this time. Most people probably thought the poor dog was a lost cause, and he certainly looked like one.

But just because a dog (or a person, many times) looks hopeless, it doesn’t mean that they can’t spring back, sometimes astoundingly, like the dog who frolicked like a puppy after having a huge tumor removed.

The rescuer took the sick dog to local animal rights activist Dalia Gamez, who adopted him, named him Boby, and set about getting him the treatment he desperately needed.

But no one could have foreseen the amazing transformation Boby would undergo.