A dog owner walked off after his pet attacked a man delivering leaflets.
Police are appealing for witnesses after the 60-year-old victim was bitten by the dog in Copthorne.
The victim was walking in Brookhill Road when he was attacked by the dog, which was being walked by another man, at about 10.30am on Monday.
The pet owner then walked off with the animal towards the Prince Albert pub.
The dog was small and white with patches of brown on its head. It had short fur and a long pointed snout.
The owner was white, about 60 and balding with short light hair. He was wearing a grey short-sleeve top and light trousers.
PC Richard Davies said: "The owner of the dog may live very close to where the incident happened so we are hopeful that someone will recognise the description of him or his animal.
"If you know who or where the man is, or you saw the dog bite the victim, please contact me."
Anyone with information should call 101 quoting serial 373 of 16/6, email email@example.com or call the independent charity Crimestoppers anonymously on 0800 555111.