Raw liver - photo reproduced under CC copyright podchef
I can remember giving raw chicken kidneys to a wandering pregnant cat. She loved them. I adopted two of her litter. That was 20 years ago. I have since become more knowledgeable on the possible defects of a raw food diet for a cat.
I guess for the exotic and tamed wild cats and their hybrid offspring a natural (i.e. at least in part, raw) diet is necessary. But for domestic cats it isn't but some love certain types of raw food. Eating certain raw foods to excess can have unwelcome side effects.
There is a condition called Hypervitaminosis A, which results from an excess of vitamin A in the cat's diet. This can happen when you over supplement your cat's diet with cod liver oil or feed her too much raw liver over a long period of time.
The condition can result in the growth of bony outgrowths in the neck and forelegs. The condition is painful, so you will notice this in your cat's mood. She will have difficulty in grooming. The cure - return to a balanced diet.
Interestingly vitamin E deficiency (as opposed to having too much) can be caused by feeding your cat too much raw oily fish (red tuna for example). These fish are high in polyunsaturated fatty acids (PFA). Vitamin E is an anti-oxidant; PFAs are easily oxidized. The effect is a depletion in vitamin E.
Vitamin E deficiency causes the hardening of the layer of fat under the skin of the cat, and the cat will dislike being touched as a consequence. She will be off her food.
Obviously the cure is once again a return to a balanced diet but apparently it can take a long time to get back to health. It goes without saying that a vet needs to be involved.
Finally, it is possible for your cat to suffer from Thiamin (B1) deficiency if you feed your cat too much of certain types of raw fish (this is because some fish contain an enzyme "thiaminase" which destroys Thiamin).
The signs are salivation and the inability to eat despite an interest in her food. This can progress to seizures and spasms of the limbs and ultimately death.
The cure - Thiamin supplement administered my mouth or injection. The improvement in her health will be rapid apparently.
Watch out for an unbalanced raw food diet for a cat even if she adores a certain type of food.
Note: I am not a vet. I have simply acquired some knowledge over a long time living with cats.