The incident occurred around 5pm on Monday April 18, at a park off Foreshore Way.
The man was left with a minor injury to his hand and arm following the incident involving a black Staffordshire Bull-terrior cross.
Police say a woman, believed to have been with the dog, is described as being 16 to 17 years old, average build, 5ft 4in tall, with shoulder length brown hair and wearing a fawn denim-style jacket.
PC McDougall of the Bo’ness Community Police Team said: “I am appealing for anyone with knowledge of this incident or information as to the owner of the dog to contact me as soon as possible.
“I would also appeal to the person with the dog to come forward and alert police as to the circumstances. I believe the animal was young in age which may account for its unpredictable nature.’’
Contact the police using 101 or Crimestoppers on 0800 555 111