Giant black dog breeds have a lifespan that is on average 10-12 years. This means that half the dogs in this category will live for 9 or more years, and the other half will only live for 8 or fewer years. There are exceptions to these averages, but as a rule, giant black dog breeds tend to have long lives. The average lifespan of a giant black dog breed is generally between 10 to 15 years. The Giant Schnauzer has a life expectancy of 12 to 14 years, while the Black German Shepherd has a life expectancy of 9 to 13 years. The Bernese Mountain Dog, a large breed, has a life expectancy of 6 to 8 years.