It is understood that three boxer dogs turned on a family in a field in Aberlemno, Angus.
Early reports suggest one of the dogs may have been shot dead at the scene.
Two other people were also hurt in the incident. The boy’s sister, aged nine, and father, aged 49, suffered serious leg and arm bites, although none of the family's injuries are thought to be life threatening.
A spokesperson for Police Scotland confirmed that officers were called to a field in Aberlemno at around 5.30pm on Thursday evening.
“A 49-year-old man, a 9 year-old girl and a 7-year-old boy suffered serious injuries in the incident and were taken to Ninewells Hospital where they remain and continue to receive treatment," the spokesperson added.
“Officers are making further enquiries into the full circumstances of the incident. Anyone with information that could assist officers with their enquiries should contact Police Scotland on 101.”
It is not yet known what happened to the other two dogs involved in the attack.