Officers attended the location at approximately 12.39pm on Sunday 21 March along with colleagues from the London Fire Brigade.
They recovered the young pup from the river bank and it was taken to a rescue centre for treatment, but unfortunately had to be put down later, due to injuries sustained in the incident. Officers are looking to identify witnesses and to speak to the owner of the dog involved.
Police enquiries continue, but we would like to thank the members of the public that stepped in to assist Freddie during the incident. The RSPCA has been informed.
Anyone with information is asked to 101 quoting reference: 0702604/21.