The Terrier Cross, which was only weeks old, was left in a field in Castleford on Saturday, March 2 without food, water or a blanket to keep warm.
When he was found he weighed less than one kilogram - less than one bag of sugar.
The poorly puppy was infected with worms and a skin disease mange, caused by parasitic mites.
He was also far too young to be away from his mother as the usual advice is that puppies must be at least eight weeks old before they are removed from her care.
It was so cold that the vets that treated him said he would have died if he was left any longer.
Thankfully, a Dogs Trust member found the puppy, who has now been nicknamed Hockney, and saved his life.
He is now being looked after at one of the Dogs Trust rehoming centres in Yorkshire.
Emma Cooper, Assistant Manager at Dogs Trust Leeds who is helping care for Hockney, said: "Puppies of this age shouldn’t be away from their mum, let alone left to fend for themselves in a field. He was immediately seen by a vet after being rescued who said he wouldn’t have survived much longer as he was so cold.
"He hadn’t even been left with a blanket. He had worms and has mange, a skin disease, which is he is being treated for.
"At first he didn’t want to eat anything but his appetite is definitely improving and he is becoming more like the inquisitive puppy he should be at his age.
"We will be looking after him for a few weeks until he has fully recovered and then we will be looking for a wonderful forever home for him where he will continue to get all the love he deserves and needs to grow into a happy, healthy adult dog."
Hockney, who is now only 5 weeks old, is too young to be adopted yet but Dogs Trust are hoping that he will be available in the next two or three weeks.
They have reminded people that they should consider the long-term commitment of a dog before bringing one into their home.
Dogs Trust has also stressed that they are there to help anyone who is worried they cannot care for their dog can speak to them and they do not need to abandon their dogs.
To find out more and keep updated on when Hockney will be made available for rehoming visit www.dogstrust.org.uk/rehoming.
How to rehome a dog from Dogs Trust
Anyone who wants to rehome a dog from Dogs Trust can visit their local centre.
Once there, the rehoming team will go through a questionnaire to find out more about the person and whether they are suitable.
Then the visitors can go and view and get to know the dogs. Dogs Trust said that it is often the case that the dog choose the person rather than the other way around.
If people are interested in a particular dog then Dogs Trust advises the person rings the rehoming centre so they can arrange a meeting.