The German shepherd was found with such a severe untreated skin condition she had virtually no fur left, in one of the worst cases found by the RSPCA.
It is the latest in a string of cases the RSPCA have dealt with and the charity expects a spike during the winter.
The dog, now named Ivy, is at RSPCA Harmsworth Animal Hospital in west London and is responding well to treatment.
A cocker spaniel puppy with a gaping open wound on his neck is another of the latest victims of animal neglect.
The black and white working cocker spaniel, now named Guinness, is thought to only be a matter of months old but was found collapsed in Grays, Essex, on Sunday with one of the worst wounds the RSPCA inspector had seen in his life.
Guinness was rushed to RSPCA Harmsworth Hospital in London for emergency vet treatment.
RSPCA inspector Joe White said: “Poor Guinness was in such a bad way when we picked him up.
“He had a huge open and infected wound on his neck and was rescued earlier this month.
“It looks as though he had been left with a collar on that was far too small for him and it had gradually cut into his neck.
“The wound was gaping and looked as though his collar had gone the whole way round his neck.
“I could not believe it - it was one of the worst wounds I have seen in my whole time as an RSPCA inspector.
“It is so deep and looks extremely painful. I have seen some awful things but this one really hit me.
“At least he is in the best place now and in safe hands getting the treatment that he needs.
“How anyone could neglect this poor puppy in this way and ignore such an awful wound that so obviously needed treatment is just beyond me.
“He is only around eight months old and so friendly and full of love despite everything he has been through.
“He didn’t even whimper when vets were treating him.
“At the moment we are trying to find his owner.
“He has a chip but the details are not up to date. On his chip he is simply known as Puppy Number 2. It is so very sad.”
The animal charity, based at Southwater, near Horsham, receives more calls about neglect than any other issue during the winter months, with on average one call every four minutes.
From October 2015 to January 2016, 45,176 neglect calls were made and last winter the RSPCA took an average of 15 calls every single hour.
RSPCA superintendent Simon Osborne said: “It’s a sad fact that every day at work throughout the year can be tough for our inspectors and animal welfare and collection officers, but winter really does come with its own challenges and issues.
“In fact, we expect to take in somewhere in the region of 19,000 animals this winter alone.
“The fact that every four minutes during winter somebody calls us to report neglect to animals is shocking, especially when you add that to all the other calls we receive at the same time about other welfare issues. It really hits home just what we are up against.
“Issues such as animals not been provided with a suitable environment to shelter from the harsh weather and not being given enough food and water to keep them healthy despite the cold and damp are common complaints made to us.”
Some of the neglect cases the RSPCA saw last winter include a four-year old pony found tied up with a chain cutting into her skin, a 12-year-old Jack Russell found with an untreated tumour the size of a football and a bearded dragon neglected so severely he developed a fatal condition.
A litter of three week-old kittens also tragically died of anaemia caused by a chronic flea infestation.