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, dry mouth), cardiac problems, seizures, epilepsy, progressive retinal atrophy (PRA), cataracts, and small ear canals with a tendency for infection.
As with most large breeds, some will suffer with elbow or hip dysplasia.

Canine inherited demyelinative neuropathy (CIDN), an inherited condition, appeared in one of the prominent lines of Tibetan Mastiffs in the early 1980s.
Unfortunately, known carriers were bred extensively and are behind many lines still being actively bred.
Because the mode of inheritance appears to be as a simple recessive, continued inbreeding can still produce affected puppies.

Hypothyroidism is fairly common in Tibetan Mastiffs, as it is in many large "northern" breeds.
They should be tested periodically throughout their lives using a complete thyroid "panel".
However, because the standard thyroid levels were established using domestic dog breeds, test results must be considered in the context of what is "normal" for the breed, not what is normal across all breeds.
Many dogs of this breed will have "low" thyroid values, but no clinical symptoms.
Vets and owners differ on the relative merits of medicating dogs which test "low", but are completely asymptomatic.
Some researchers think that asymptomatic hypothyroidism may have been adaptive in the regions of origin for many breeds, since less nutrition is required for the dog to stay in good condition.
Therefore, attempts to eliminate "low thyroid" dogs from the Tibetan Mastiff gene pool may have unintended consequences for the breed.
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, dry mouth), cardiac problems, seizures, epilepsy, progressive retinal atrophy (PRA), cataracts, and small ear canals with a tendency for infection. As with most large breeds, some will suffer with elbow or hip dysplasia.
Canine inherited demyelinative neuropathy (CIDN), an inherited condition, appeared in one of the prominent lines of Tibetan Mastiffs in the early 1980s. Unfortunately, known carriers were bred extensively and are behind many lines still being actively bred. Because the mode of inheritance appears to be as a simple recessive, continued inbreeding can still produce affected puppies.
Hypothyroidism is fairly common in Tibetan Mastiffs, as it is in many large "northern" breeds. They should be tested periodically throughout their lives using a complete thyroid "panel". However, because the standard thyroid levels were established using domestic dog breeds, test results must be considered in the context of what is "normal" for the breed, not what is normal across all breeds. Many dogs of this breed will have "low" thyroid values, but no clinical symptoms. Vets and owners differ on the relative merits of medicating dogs which test "low", but are completely asymptomatic. Some researchers think that asymptomatic hypothyroidism may have been adaptive in the regions of origin for many breeds, since less nutrition is required for the dog to stay in good condition. Therefore, attempts to eliminate "low thyroid" dogs from the Tibetan Mastiff gene pool may have unintended consequences for the breed.
Tibetan Mastiff