Tibetan Mastiffs are shown under one standard in the West, but separated by the Indian breed standard into two varieties: Lion Head (smaller; exceptionally long hair from forehead to withers, creating a ruff or mane) and Tiger Head (larger; shorter hair). Temperament As a flock guardian dog in Tibet, and in the West, it uses all the usual livestock guardian tactics (e.g., barking, scent-marking perimeters) to warn away predators and avoid direct confrontations. Tibetan Mastiffs can run up to a speed of over short distances. As a socialized, more domestic dog, it can thrive in a spacious, fenced yard with a canine companion, but it is not an appropriate dog for apartment living. The Western-bred dogs are generally more easy-going, although still somewhat aloof with strangers. Through hundreds of years of selective breeding for a protective flock and family guardian, the breed has been prized for being a nocturnal sentry, keeping would-be predators and intruders at bay, and barking at unidentified sounds throughout the night. Leaving a Tibetan Mastiff outside all night with neighbors nearby is not recommended. They often sleep during the day, making them more active, alert, and aware at night. Like all flock guardian breeds, they are intelligent and stubborn to a fault, so obedience training is recommended (although it is only mildly successful with some individuals) since this is a strong-willed, powerful-bodied breed. Unless they are to be used exclusively as livestock guardians, socialization training is also critical with this breed, because of their reserved nature with strangers and guardian instincts. They can be excellent family dogs, depending on the family; owners must understand canine psychology and be able and willing to spend a lot of time and devotion to training their dogs. Lack of consistency can result in the creation of unpredictable dogs. The protectiveness of Tibetan Mastiffs requires alertness and planning by the owner, in order to avoid mishaps when the dog is merely reacting as a guardian. The breed is not recommended for novice dog owners. Health Many breeders claim a life expectancy of 10–16 years, but these claims are unsubstantiated. Some lines do produce long-lived dogs. Other, more closely inbred lines, produce short-lived, unhealthy dogs. The breed has fewer genetic health problems than many breeds, but cases can be found of hypothyroidism, entropion, ectropion, distichiasis, skin problems including allergies, autoimmune problems including demodex, Addison's disease, Cushing's disease, missing teeth, malocclusion (overbite, underbite,