Its unfortunate there is not alot of physical data to support raw,
It's unfortunate that there's not a lot of physical data on dog nutrition in general for that matter. Up until recently dogs weren't necessarily considered part of the family, but more like livestock, or just working animals. So people fed what they could feed, meat scraps and whatnot (and oddly enough dog's lifespans - assuming they didn't die of injury or illness - were not much different than now). When people started keeping dogs more as family members the big corporations jumped right into the market (Nestle, P&G, etc.) to make cheap foods that they marketed as highly nutritious with lots of advertising so people would buy. This was a good way for the companies to use their leftovers (non human grade meat byproducts, grain leftovers and stuff like that). It became generally cheaper and more convenient for people to buy pet food in a bag or a can than to prepare their own foods.
It's only very recently that more than a few companies have jumped into the market with better food formulas and people have started to question the ingredients in big name pet foods. Hopefully now that there are more and more people wondering about pet nutrition there will be more unbias studies done into canine and feline nutrition.