The alleged incident took place at around 10:30 on Thursday 15 August in in Long Beach car park.
The young boy sustained “a small wound to his upper thigh”, according to police.
In an appeal for information, police said that a woman was walking two dogs, when one of them – a large brown dog – bit the child on his leg.
The lady recalled the dogs back and put them in her car before driving off.
Police said: “The little boy sustained a small wound to his upper thigh and was checked out at the Emergency Department.
“He was fine and did not require any further treatment.”
The dog owner is described as a middle-aged woman with short blonde hair. She was driving a small blue car.
CAN YOU HELP?
Anyone who may have seen this or who has any information is asked to contact police on 612612, or the independent charity Crimestoppers anonymously on 0800 555 111, or via their anonymous online form at Crimestoppers-uk.org.