Inspector Richard Quinn, from Cumbria Police said:
"The dog is currently in our care. Because a child is involved we need the full facts before we can determine what should be done with it.
"At this stage we haven't had an opportunity to interview the parents but we believe this may have been a terrible accident."
More top news
Emma Jesson brings you Saturday night's forecast
Sunny spells and snow showers. Bitter east wind with overnight frost and ice
The victim initially thought strangers Kabir Hussain and Marco Martins were trying to help her as she left a pub in the early hours.