The girl, Karnamoni Handsa, had to be married quickly because she had a tooth rooted to her upper gum, which is considered a bad omen by her Santhal tribe in the remote village of Khanyhan, about 60 kilometres (37 miles) from Calcutta.
"Members of the village jury asked us to get her married to a dog or to face the bad omen," the girl's father was quoted as saying by the AFP news agency.
The tribe elders said the marriage would not affect the girl's life, and that she would be free to marry again later and did not need to divorce the dog.
"It will not spoil her future. We will marry her off to eligible bachelor when she grows up," the girl's mother told AFP.
The wedding - which took place on 11 June - was attended by more than 100 guests, who danced to the beating of drums and drank home-made liquor.
"I have no regret in marrying the dog Bacchan. I am fond of the dog which moves around our locality," the girl told the AFP.
"Bacchan is a stray dog which survives on left-overs. I will take care of the dog," she added.
Indian newspapers reported that local police officials had ordered an inquiry into the incident.
The Santhals - most of whom are sharecroppers - are a large tribe living in the states of West Bengal and neighbouring Bihar and Jharkhand.