The 23-month-old boy was bitten by a black Staffordshire bull terrier in Kirriemuir, Angus, on Wednesday afternoon.
He remained in hospital last night, but his condition was not thought to be life-threatening.
Eyewitnesses said the boy’s mother rushed the screaming child into a nearby health centre following the attack.
Police are looking for a woman who is thought to be the dog’s owner in connection with the incident.
Sarah Mackie, 24, said she had been in the health centre when the boy was brought in by his mother. She said: “He was in a real state, crying and screaming with blood streaming down the right side of his face.
“Everyone who was in the health centre at the time was really upset and shocked by what they had seen.”
CONNECT WITH THE SCOTSMAN
• Subscribe to our daily newsletter (requires registration) and get the latest news, sport and business headlines delivered to your inbox every morning
A doctor from the centre was able to tend to the boy before an ambulance arrived.
The ambulance service said the boy had been conscious and breathing before he was taken to Ninewells Hospital in Dundee.
A police spokeswoman said: “Police Scotland are appealing for information after a 23-month-old child was bitten by a black Staffordshire bull terrier dog. The incident happened at about 1pm in Glamis Road.”
Officers are trying to trace a woman who is thought to be in her twenties, with light brown/blonde hair, who was wearing a red top.
Kirriemuir resident Alison Lothian, 53, who owns a “Staffie”, said: “You tend to find it is normally the owners of these types of dogs that are the problem.
“These are strong dogs and can be wound up by people who deliberately try to make them aggressive.
“It is certainly not a common thing for these dogs to go around attacking people.”
Ian Robb, from Angus Dogs Rescue, said: “Sometimes it is not the dogs who are at fault but the owner. Dogs can become jealous around babies or can sometimes think children are in distress. Their owners have to be very careful.”
The incident comes amid calls for the law on dog ownership to be tightened to try to prevent children being attacked.
Labour MSP Paul Martin put forward a series of proposals earlier this year after eight-year-old Broagan McCuaig was mauled in Glasgow last year by two American bulldogs.
The Scottish Ambulance Service also confirmed that paramedics attended the scene at Kirriemuir Health Centre.
SCOTSMAN TABLET AND IPHONE APPS