A dog that had been ordered euthanized Wednesday by Mansfield selectmen after he bit a 6-year-old boy in January attacked a teenage girl Saturday, Mansfield police said in a statement. The 16-year-old girl was taken to Hasbro Children’s Hospital in Providence after she was bitten by Milo, a 3-year-old pointer-hound mix. Police did not identify the girl and her condition was unknown. The boy who was bitten in January needed more than 400 stitches. Olivier Kozlowski, chairman of the Board of Selectmen, said Milo was allowed to stay with his owner, Michael Bailey, for 10 days following the board’s decision to euthanize the dog, during which the family could appeal. The family let an animal control officer take Milo Saturday night after the dog bit the teen, Kozlowski said.