The Mastiff is a particularly large dog demanding correct diet and exercise. Excessive running is not recommended for the first two years of the dog's life, in order not to damage the growth plates in the joints of this heavy and fast-growing dog, which in some weeks may gain over 5 lb. However, regular exercise must be maintained throughout the dog's life to discourage slothful behaviour and to prevent a number of health problems. A soft surface is recommended for the dog to sleep on to prevent the development of calluses, arthritis, and hygroma (an acute inflammatory swelling). Due to the breed's large size, puppies may potentially be smothered or crushed by the mother during nursing.