Taurin is an amino-acid, so part of the protein needed by both cats and dogs. Only, for cats it is essential – cats cannot produce it and dogs can. A dog produces taurin on the basis of other amino-acids. Fresh or frozen meat contains the taurin a cat needs. So both in nature and natural food this is perfectly arranged.
The main problem with taurin is that it is very sensitive to high temperatures. Particularly in combination with moisture, pressure and friction, things that – as already mentioned – play a big part in the preparation of canned and dry food. A distinction is therefore drawn between cat and dog food for commercial reasons.