It is common knowledge that large dog breeds tend to have shorter lifespans (generally around 10-13 years; for the wolfhound and the great dane, as low as 7-8 years) than smaller dog breeds (some of which can go on for as long as 15-20 years). In fact, one study found that within 74 different breeds, dogs lose about one month of life expectancy per 4.4 pounds (2 kg).
So why does this happen?
