Among the largest of all dog breeds, full-grown mastiffs can top 200 pounds, standing 30 inches high at the shoulder. Although large, these gentle giants aren't that common, so if you're in the market for a mastiff puppy from a reputable breeder, you might have to wait a while.
A mastiff might give birth to only one puppy in a pregnancy, but litters of up to 16 puppies have been reported. In between these two extremes is the average litter size, which is about eight puppies. These puppies grow fast, so if you're planning to breed your female mastiff, allow mother and offspring ample room.
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