The infant's mother told police that she left the girl alone briefly in a bassinet Wednesday night while she used the bathroom in their Mesa home, The Arizona Republic reported. While she was out of the room, the dog, a Chow mix, bit the baby on the head.
By the time paramedics got to the house, the baby had died.
Police did not release the identities of the parents but said that both are police officers, the father in Mesa, a suburb of Phoenix, and the mother with the Salt River Pima Maricopa Indian Community Police.
"They are like any other parent can imagine -- they are absolutely devastated by the loss of their baby girl," said Mesa Police Detective Steve Berry, the newspaper reported.
Chows or Chow Chows are one of the oldest known dog breeds, first bred for hunting in Mongolia about 4,000 years ago and spreading from there to China. They are small, less than 2 feet long, but sturdily built. They are known for bonding tightly to their human families and being aggressive to perceived strangers.