A frail dog left without food or water for days was too weak to walk when Hillingdon Police went to rescue the pup.
Officers attended an address with the RSPCA in the borough after reports of a dog being left alone.
After gaining entry, they found that the dog - whose name and breed is not yet known - had no food or water for at least six days.
A Metropolitan Police officer said: "After receiving a call, PC Johnstone and PC Joshi attended an address to support the RSPCA.
"The dog was found to have no food or water and clearly had been abandoned for some time."
PC Johnstone has for now called the small dog "Dog" and she has been taken to the RSPCA to help her recover.
The officer had to carry her in order to take her out from the property as "she was too weak to walk", Hillingdon Police said.
The police added: "The RSPCA will be dealing with the owner appropriately."
A spokesman for the RSPCA told getwestlondon : "The RSPCA’s dedicated staff and volunteers work 24 hours a day and sadly, there are always animals that need us and there are also thousands in our care who need looking after."
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