Many people believe that milk jugs, glass or other empty containers can deter both dogs and cats from their lawn.The milk jugs are not filled with milk, of course: The milk would only attract dogs and cats as it spoiled.mell. Mixing some ammonia or mothballs with water in the plastic jug is believed to deter dogs. Dogs are evidently annoyed by the smell and will stay away from the lawn that is emanating that smell.