The female dog had a large mammary tumour which was ulcerated and had been covered over with a piece of kitchen roll. A silver bowl containing cooked chicken was by her side.
She was found on Monday morning in a copse of trees off a car park by Winscar Reservoir in Dunford Bridge.
RSPCA deputy chief inspector Jennie Ronksley said:
“The presence of the dog bowl suggests this poor girl was alive when she was left here.
“She wasn’t tied to anything and there was a piece of kitchen roll covering the burst tumour so I suspect she was in a collapsed state.
“While this area is popular for walkers and there is a path leading to a sailing club very nearby, it is still relatively remote.
“I think she had died no longer than 24 hours before being found.”
The dog wasn’t wearing a collar and ID tag and wasn’t microchipped so at the moment there is no way of tracing her owner.
“Aside from the tumour there were no other signs of neglect, she was in good body condition, a good weight with a good coat of fur,” said DCI Ronksley.
“It’s extremely sad.
“It seems to me as though her owners did love her, and - though absolutely no excuse for leaving her alone and exposed to the elements like this - perhaps felt they couldn’t afford the veterinary care she very clearly needed.
“I’m hoping that someone will recognise this dog and get in touch, perhaps even her owners themselves.”
If anyone has any information please call the RSPCA inspector appeal line on 0300 123 8018 and ask to leave a message for DCI Ronksely.