A Fitchburg mother and her 3-year-old daughter were injured after being attacked in their home by a dog described as a “pit bull breed,” according to Fitchburg police. The dog, which belonged to another resident of the multifamily house on High Street, bit the toddler in her left ear and the back of her head, said police Sergeant Glenn Fasso. The mother tried to stop the attack and suffered a more severe injury to her left forearm. Another occupant of the house stabbed the dog with a kitchen knife to halt the attack. The dog was euthanized, Fasso said. The toddler was being treated at HealthAlliance Hospital in Leominster and the mother was hospitalized at UMass Memorial Medical Center in Worcester, Fasso said.