Generally, larger mammals live longer than smaller ones.  However, new research examining the link between growth and mortality has shed light on why large breeds of dogs die at a younger age than small breeds of dogs. Scientists found that large breeds age at a faster rate.  This speed increases the risk of death for bigger dogs.  They found that among breeds of dogs, an increase of 4.4 pounds leads to the loss of roughly 1 month of life expectancy.  The accelerated rate of aging could also explain why big dogs get cancer more often than small dogs.  See more at Live Science.

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