One of the three huskies that was in the house at the time of the incident is seen with its owner Monday night. (CBC)A 17-year-old mother was charged with manslaughter on Tuesday after a dog mauled and killed her newborn girl east of Montreal.

The teenager and her 37-year old mother were arrested late Monday after the three-week-old baby was killed by a husky inside the family home in Saint-Barnabé-Sud, near Saint-Hyacinthe.

Paramedics found the baby girl covered in deep bite marks and scratches. Police said she had been left strapped in her car seat on the main floor of the house when one of two dogs in the home attacked her.

The teen was charged in youth court because she is a minor and cannot be identified.

The woman's lawyer, André Williams, said he was "completely blown away" by the charge laid against his client and by the speed with which it was laid.

"This is a young girl who is rather fragile," he told reporters at the Saint-Hyacinthe courthouse on Tuesday.

On Tuesday afternoon, the baby's grandmother was released after the Crown decided there was not enough evidence to press charges, said the woman's lawyer, Mélissa Côté.

The baby's father, centre, is surrounded by friends outside the St-Hyacinthe courthouse on Tuesday. (CBC)The 37-year-old woman was visiting her daughter and granddaughter Monday afternoon.

The women left the house to go outside "and go in the garden to see the flowers," said provincial police Sgt. Ronald McInnis.

The infant was left inside the house strapped into a car seat that was sitting on a chair.

The women were about three metres away from the home with the door open when the baby was mauled.

Police had initially said both women would be charged with criminal negligence.

The upgraded charge of manslaughter against the mother indicates that the Crown intends to prove that there was a criminal act committed that brought on the death of the baby, rather than sheer negligence, said criminal lawyer Conrad Lord.

"The evidence is so hard to prove in a case like that, where the mother did not hit the child, so there is no proof of evidence of any mistreatment of the child, but death occurred because of [an act] that was committed," he said.

Baby's mother not to blame: father

The baby's father said that he does not blame the child's mother for the incident, which happened at the home the couple shared with at least two other people.

He said the two women had just stepped a few feet outside for a smoke and ran back inside the house as soon as they heard a noise. But it was too late.

"It was just a moment of inattention," the man, who cannot be identified, told reporters on Tuesday. "I hope she will be acquitted, because she had nothing to do with it; she was an excellent mother."The mauling happened in a family home in Saint-Barnabé-Sud, about 60 kilometres east of Montreal. (CBC)

The man said there were three dogs inside the house: a male and two females, one of which was in a cage with young puppies.

He said the women were too shocked to see which of the two loose dogs was responsible for the attack.

The dogs had been around since the baby's birth and had never posed a problem, he said.

"They weren't aggressive," he said. "When strangers came to the door, they didn't even bark. There was no sign that this could happen."

Because the father was not at home at the time, he won't face any charges, police said.

Dogs must be supervised around children

The huskies were taken to the SPCA for testing and will not be returned to their owners, police said.

It may be impossible to know for sure why the dog attacked the child, said veterinary behaviourist Enid Styles.

Dogs are more likely to bite older children, because they have unpredictable movements that can frighten the animal, she said.

However, Styles said it is possible the animal might have been startled by the child's crying or the baby might have been caught in the middle of a fight between the dogs.

In any case, a child should never be left unattended around dogs, Styles said.

"Supervision needs to mean, really, that you are between your dog and your child," she said. "You can't be just on the other side of the room."

The mother will be back in court on Aug. 31.

As part of the conditions of her release, she is not allowed to look after children under the age of 12.

With files from The Canadian Press