Differing animal weights in relation to life span

Question

How come smaller dogs generally havw longer life spans than larger dogs, but larger animals, like horses, have an even longer lifespan?

In: Biology

Answer 1

There is a rule of thumb that smaller animals have shorter lives and bigger animals have longer lives (though it has many exceptions, like parrots and humans). But breeds of dog are all the same species we have made different through rapid selective breeding, and when you breed them to be very large they burn way more calories than their metabolism “expects” and build up damage quickly.