From Visual Economics: How Much Our Pets Cost in a Lifetime - theirs. I'm not sure about the numbers or this visual of a reddish pink Big Dog with a deformed head.
If you thought big dog = big expenses, we can’t fool you. Big dogs tend to cost a lot more, and their average life expectancy isn’t much shorter than a medium dog’s. Big dogs cost $700 a year, with first year expenses adding up to a whopping $1,500. Over the life of your big guy or gal, that comes to $7,800. But the slobber and attention is free!