I met a couple I know with their newly rescued dog. He was emaciated and had lots of fur missing. He had been found in the city and the vet thought he had been abandoned weeks or more ago.
A month or so later when I saw him he was putting on weight and was so much happier.
If it's worrying you report it. I f it is a rescue dog no harm done but if it's being neglected then RSPCA needs to know.
Unexpected opportunity to have a few days break next week and would love some recommendations


