While it's not uncommon for mastiffs to live 10 to 11 years, the average life span of a mastiff is seven years. This large, heavy breed, noted for its loyalty and gentle temperament, requires two or three small meals a day and regular exercise to prevent health problems.
Typical major health problems for mastiffs include hip dysplasia and gastric torsion in which the stomach dilates and then twists on its axis. Minor problems include obesity, osteosarcoma and cystinuria, a genetic kidney defect. A soft sleeping surface helps prevent calluses, arthritis and inflammatory swelling. Mothers must be carefully monitored when nursing pups to prevent accidental crushing under their weight. Adult females weigh an average 150 pounds, and males average 160 pounds, although some males reach 200 pounds or more.