A woman watched in terror as a dog savaged her pet Yorkshire terrier leaving it badly wounded.
The incident happened in Carshalton Park at 9.15am on Wednesday, July 30.
The woman was walking her pet when a large brown dog attacked it leaving it with cuts to its eyes and he ad that needed treatment from a vet costing £60.
The woman spoke to the owner of the dog who said she was in the area from Scotland visiting her mum in Carshalton.
She told the woman where her mum lived but it turned out to be a fake address.
Police are keen to speak to the woman who is white, aged 45 to 60, about 5ft 4in and with shoulder length blonde hair. She was wearing shorts and a T-shirt.
If you have information, you can call police on 101 or the charity Crimestoppers on 0800 555 111.