The police were called around 9.15pm on June 17 to Mountfield Park.
Officers arrived, but the dog later died as a result of its injuries.
A poster shared about the incident alleges that the attacked dog was a greyhound called Juno.
It adds that “the injuries were so severe she [Juno] had to be put down” following the “brutal” attack.
The Met Police has launched an investigation and enquiries are said to be ongoing to identify and find the other dog and its owner.
Anyone with information is asked to contact police using reference CAD 8545/17June.
A Met spokesperson said: “On Tuesday, 17 June at 21:13hrs police were called to reports of a dog attacking another dog at Mountfield Park, SE6.
“Officers attended the scene and made enquiries. The dog sadly later died from its injuries as a result of the attack.
“An investigation has been launched and enquiries are ongoing to locate and identify the other dog and their owner.
“Anyone with information that could assist police is asked to call 101 quoting CAD 8545/17June.”
