I don't know, really. But. Some commercial food companies sell foods that are supposedly complete and balanced for both cats and dogs, the same food I mean. The food, supposedly, is geared toward proper balance for the CAT, which apparent;y follows that it will be fine for the dog too.
It doens't work the other way though, a food balanced for a dog may not necessarily be balanced for a cat.
So having said all that, I guess my answer is still "I don't know".