The woman was running on the Common with her dog on Monday the 18th December at around 9:25am when the incident took place.
The victim was bitten on the hand and her dog was also attacked.
The owner of the dog is described as White, aged between 60-70 and of a short, stocky build. The dog is also described as short and stocky.
Officers are asking any witnesses of the incident or anyone with information to come forward and contact them on 101.