Ruislip resident, Stephanie Jost, whose mother found the cat told the website that her mum had been “beside herself” following the discovery.
She added: “It has left my mother and I in shock and we are terribly sad in the knowing that someone will be missing their feline friend.”
The RSPCA confirmed the find had been referred to a dedicated team working to investigate a spate of similar cat deaths across the capital.
A spokeswoman told the Standard that the animal’s head and tail “appeared to have been removed by a human”.
She said: “Evidence suggests there is a clear link in the nature of the deaths.
“Experts have said likely cause of death was blunt force trauma, likely caused by a road traffic accident although it is difficult to be sure. The heads and tails appear to have been removed by a human.
“Please be reassured that we take all reports of animal cruelty very seriously, and are extremely keen to get to the bottom of these upsetting deaths.”
Anyone with any information is asked to contact DS Andy Collins at the Metropolitan Police on 0208 6490216 or contact the RSPCA by calling 0300 123 8018.