We feed our dogs BARF... which means bones and raw food. They thrive and have wonderful clean teeth and fresh breath. Their poops are small and break down in the backyard quickly.
I looked into BARF for cats. They require some weird additive (it's probably in raw mouse guts which is not easily available in stores) so I got some of the suppliment and tried mixing it with ground liver, gizzards, etc. They hated it. They much prefered the IAMS dry cat food.
The amino acid taurine is required by cats and is not present in some of the usual protein sources.
Our dogs eat all raw, too!