Dogs haven't evolved to eat totally dried out food which can increase the risk of bloat especially in the case of mixes heavy in cereals. Also usually there is a greater amount of complex carbs in dried food which they do not need.
Sorry Kitsune (I'm not doing this very well am I?) I meant why would you supplement the dry diet? Is it personal choice or do you think that the dry food is lacking?
I believe that a diet that best replicates what dogs are meant to eat, is a varied one.
Fish provides some great oils, fresh meat the same. Bones, marrow etc all provide something which dry or wet food cannot supply. Although I'm not scientifically sure what that is, but I know through cooking etc met loses some of its goodness.
Well, my dog can't really eat either - she's intolerant to every cereal I've tried, the only carb source she can tolerate is potato and there's so few kibbles out there that use that instead of wheat or whatever.
However, as a sweeping generalisation, dry every time. I've known too many dogs with rotten stinking mouths and no teeth from living entirely on wet food, plus as Kitsune says their poo is atrocious. You can see the Pedigree Chum Poos from a mile away in the park, 'cos they're in gigantic soft orange heaps.
Out of those two choices, Dry.
Otto is fed on Acana Dry food and he has never had such nice poop, RAW is the next step once we have a freezer and somewhere to buy it from!