1. Yorkshire Terrier
They are quite small in size but with very large personalities. Even though they can be extremely protective and territorial, they are also very playful and sociable. They do not shed despite having long, thick and luxurious fur. However, they require regular grooming and brushing to keep the silky hair clean. These dogs are also very alert. They will bark when they see any danger. Therefore, you need not worry about any intruder.