The border collie, named Jack, was found buried somewhere in the Scottish highlands - the exact location hasn't been revealed.
The pooch was saved after passing hillwalkers heard him crying, and was found to have multiple skull and jaw fractures when vets took him in.
He also had to have surgery to remove the damaged to his eye and teeth.
The pup was found "on the brink of death" and needed weeks of veterinary care.
Describing tending to the scene, animal helpline and inspector Yvonne Sloss said: "This was truly one of the worst cases I have ever experienced.
"When I first saw Jake I felt shock, sadness and disbelief that someone had deliberately done this to him.
"His head was so swollen and he was in a terrible way. We didn't think there was any way he would make it."
"He was in a comatose state when we arrived at the vet where he received emergency treatment.
"Miraculously, Jake survived the night. It was only when he was transferred to our Glasgow vet clinic that we found out how bad it actually was.
"Poor Jake was in need of a lot of care to help him recover both mentally and physically."
He had to have treatment for almost six weeks to recover from the horrible injuries he had obtained.
The dog was given the name Jake after being taken in, and he has now found a new forever home with SSPCA inspector, Mark Greener - who was also at the scene.
He said: "Jake required specialist care and it took time for him to come round and really heal.
"It took him a while to trust me but now that he does, we're bonded forever."
Mr Greener added: "We are always outside and Jake loves to play.
"I really couldn't imagine life without him now. I'm so thankful to the passers-by who found Jake. Without them he may not have survived that day."
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