Dogs (and wolves) do not have the enzymes to digest raw vegetables. It would make sense that in theory wolves could eat the stomach contents of their kills because those greens would've already had some enzymes on them in order to break down and digest the actual green. But I doubt this happens as it would be pretty hard to choke down some of those acids and enzymes.
That being said...blanched or thoroughly blended vegies will get some rate of absorption in canine digestion. Not all, but some. And although they don't need it, it can't hurt to get a few extra vitamins and nutrients that aren't present in meat. It's not a necessity, but it won't hurt them either. Some vegetables are wonderful for clearing up digestive issues...when my boy gets the runs, we just give him a few tablespoons of pureed pumpkin and it clears it up faster than any medicine the vet has ever given us.
I wanted to add...if not for the cost and the storage space needed to buy in bulk, I'd be doing raw. At the moment we just feed a high quality kibble. We used to do pre-made raw, but had to stop due to some food issues. Can't say I've noticed a difference with anything in my boy since he's been on 100% kibble. With some dogs, depending on the problems, you'll see huge improvements, but with others, it really won't affect them at all. In fact...my boy needs carbs to slow down his digestive process or otherwise he gets hungry in the middle of the night and starts to puke bile. We noticed feeding him kibble slows this down considerably and he can then make it to the morning meal.
Last edited by martemchik; 01-24-2013 at 04:54 PM.