High Protein does not cause kidney disease. From the
LBC website:
Recent research suggests a link between vaccination for feline distemper and immune-mediated inflammation of the kidneys, which is thought to be the cause of CRF. Annual boosters for distemper are completely unnecessary. Be sure to discuss all recommended vaccines with your veterinarian. A cat with kidney disease or kidney failure should not be vaccinated at all.
Long-term feeding of an all-dry-food diet is also suspected as a factor in Chronic Renal Failure. Cats' kidneys are highly efficient and adapted to life in the desert, where they would get most or all of their water from eating their prey. Cats eating dry cat food take in only half the water that cats on a canned or homemade diet get; this chronic dehydration can cause stress on the kidneys over time. Dry diets also predispose cats to lower urinary tract disease (FLUTD, LUTD, FUS, crystals, stones, cystitis) because they force such a high degree of urine concentration.
Chronic or recurrent bladder disease may also be a factor in the development of CRF.
Low protein diets are useful in alleviating the symptoms of a cat in late stage renal failure, but they are NOT recommended for healthy or early stage cats with Chronic Kidney Disease because they cause muscle wasting and adversely affect the cats' overall health. Current research shows that a
high-quality protein (no byproducts), low phosphorus food is better suited for cats with kidney disease, with the exception of end-stage cats. A higher quality protein source means that the kidneys don't need to work as hard filtering the protein metabolism residue.
Because one of the key factors in the development of kidney disease is\ chronic dehydration,
you do not want to feed any dry food. Dry food is moisture depleted and contributes to chronic dehydration.
Kidney disease is often not detected by vet tests until the cat has lost about 70% of their kidney function, so it may be a good idea to feed a high quality, low phosphorus canned food to an senior cat. A low phosphorus diet won't prevent kidney disease, but it will help slow the progression if it's already there in an early stage. And reducing strain on the kidneys will help prevent further damage as well.
Fancy feast is very high in phosphorus and contains byproducts, so if you have a senior kitty and you want to be proactive with the kidneys, I would opt for a low phosphorus, high quality protein food.
Did you see my response in your other thread on IBD?
http://felinediabetes.com/FDMB/viewtopic.php?f=28&t=74732. Several of the foods I recommended there are low carb, high quality protein, and low phosphorus. I think they would suit the health needs of all your cats.