its my guess dogs shouldnt eat so much meat products look how hard many strain to take a shit, if dogs were fed better theyd live longer id think
osteoperosis is highest in eskimos who eat mainly meat and bone meal BTW
Dogs are carnivores...and their size (a carnivore's size) tends to coorelate to the size of their prey...so, in theory a large great Dane or St. Bernard (and them being pack animals) would probably be feeding on animals that are the size of large deer, moose, elk. And their has to be enough to go around for the whole pack.
Take a look at a Lion Pride, where the females average well over 200 pounds, plus a male or two that weighs over 500 pounds---they need more than one wilderbeest kill, many times they have to kill multiple times or kill a cape buffalo.
And wolves are built for running. Legs that are too long don't help, and body sizes that haven't evolved thru natural means don't help either. Man breed dogs to benefit his needs, nature breeds animals to survive...and not even that is a perfect process. Look at Smilodon (sabre tooth cat). Many skeletons have shown excessive wear on the hip bones/joints. This was due to overtorquing of the hips in bringing down prey.