Feeding the Kidney Patient: The Low Protein Diet Myth


Last Updated on February 7, 2023 by Will Falconer, DVM

Feeding the Kidney Patient: The Low Protein Diet Myth

Low Protein Diets? Really?

The Skinny On Kidney Disease

Kidney disease. This one way street eventually leads to death. We see it in our cats most often, much less in dogs, and I suspect far, far less in horses. People die of this regularly. Unlike the liver, with its massive capacity for regeneration, the kidney simply doesn’t allow for renewal. Once kidney failure (or, more politely, CKD chronic kidney disease) is diagnosed in your animal, it means 75% or more of the kidneys’ capacity to filter wastes is now lost. Failure is the operant word, though. These two small organs are in failure and won’t pull out of it.

Luckily, homeopathy offers quite effective palliation.

Palliation means, in any treatment modality, that as long as treatment continues, the disease symptoms are minimized and the animal feels and acts pretty well. While we’d rather cure, in which the disease is, in Hahnemann’s words, extinguished, this organ doesn’t allow us this grace. What’s damaged stays damaged, unfortunately.

Palliation, in our group experience among homeopathic vets and animal caregivers, is a close second to cure in these animals. We must find the best fitting remedy and give it repeatedly, usually once daily, and in so doing, these guys stay comfortable and happy. They slowly, ever so slowly, waste away, getting bonier spines and more haphazard appetites until they finally succumb, usually without fanfare. I’ve had renal failure cat patients live for five years or more on a remedy, fluids, and an appropriate diet.

More on that last piece in a minute. Myths abound about low protein diets being a necessity.

These animals show a steady increase in thirst and a paler and paler urine color on the way to the end. This is a function of the filtering capacity of the kidney being lost, damaged by inflammation. As the wastes are less efficiently eliminated, we see these animals:

  • Urinating more often, in larger quantity

  • Becoming increasingly thirsty

  • Vomiting more often

  • Getting dehydrated

  • Sleeping more of the time

  • Losing weight

But what causes this inflammation? For this, a story of vaccine development is necessary.

The Cats are Talking: Causation

All vaccine viruses need cells to grow on during their manufacture. Like growing those colonies of bacteria that you’ve seen on an agar plate, organisms of disease are cultured to be turned into an injection. In cats, who get this disease more than most, what cells were used as a culture medium?

Feline kidney cells!

And guess what kind of protein washes into the final product with the vaccine viruses that are harvested? You guessed it: feline kidney protein.

Inject someone else’s kidney protein into your cat, and what do you get? Right again: antibodies that are made to attack kidney cells! Here’s the study that proved that, from 2005.

Darn. Sounds a lot like we’re setting the poor cat up for kidney disease by vaccinating, doesn’t it? This is but one reason I call this your biggest decision ever.

The Low Protein Diet Myth

So, we see chronic kidney disease is yet another man made disease. Helped along by dry food, which you should stop feeding. Yesterday. Here are several reasons why.

But here’s the persistent myth:

Kidney failure patients must eat a low protein diet!

This is preached like gospel in every conventional veterinary practice on the planet. An impressive sounding line of foods called “Prescription Diets” has sprung up around manipulating foods to impact diseases, and Hill’s K/D is, you guessed, Kidney Diet. And it’s widely “prescribed” (catch the marketing angle there?) by well meaning vets if there’s even a remote chance that your animal has kidney disease.

It appears a rat study may have been the impetus for this myth to run rampant throughout veterinary medicine.

And rats are herbivores. The findings do not apply to cats, an obligate carnivore, with a completely different metabolism. Or even the dog, whose ancestors and wild cousins eat prey and do very well, thank you.

Here’s what we know, from some completely non-scientific but significant experiences in cat households.

What Happens Outside the Lab?

Cats in multiple cat households, who were diagnosed with kidney failure, often craved the healthy balanced raw diets that their cohorts were eating. A number of owners, knowing their cats had a fatal disease, thought, “Well, you’ve got a death sentence anyway, here, go ahead and enjoy some raw food along with your tribe.”

And, given the chance to eat raw, high protein, supposedly damaging to kidney diets, these cats flourished!

The kidney failure cats eating raw, high quality, high protein diets:

  • Got shinier coats

  • Lost their finicky appetites

  • Had more energy

  • Had less vomiting and nausea, a common effect of kidney disease

  • Gained weight

When I learned this anecdotally from colleagues, did I wait for the double blind studies to come out to “prove” this? Hell no, I told it to everyone in my practice who brought me a kidney failure animal. And, apparently also not having read any studies to the contrary, every one of them has improved!

Why?

Perfusion: Get That Blood Moving

It’s widely known that relatively higher protein diets improve the blood flow through the kidney. Aka perfusion, that’s a good thing if your animal’s kidneys aren’t doing such a great job of filtering wastes. The more blood that gets into even a failing filter, the more chance there is to get the toxic waste products out.

And the opposite is true: low protein diets decrease this blood flow or perfusion. This actually showed up in the rat study linked to earlier. GFR is mentioned, and that stands for glomerular filtration rate, or the rate at which the tiny functional unit of every kidney, called the glomerulus, is doing its job of filtering.

In addition, kidney cell death increases when the circulation through the kidney is compromised, as you might imagine. Blood flow is a good thing in every organ. In with the good (oxygen, nutrients), out with the bad (waste products, toxins).

You’ll know when your animal is getting intoxicated from poor filtering of toxins. These are the cardinal signs that CKD animals show periodically throughout their illness:

  • Vomiting (You remember your young and foolish days with alcohol intoxication? Same idea.)

  • Lethargy

  • Poor appetites

Though this is beyond the intent of this post, these are indications to give your animal some subcutaneous fluids. It can be done at home with a bag of fluids and some instructions from your vet. Don’t miss the opportunity to do this. You will improve your animal’s health almost immediately by giving fluids when intoxication and/or dehydration has set it.

Crappy Protein vs. The Real Deal

A common observation in holistic vet practice is the vast improvement that comes from changing from a kibble to a raw diet. In any animal. But this is especially true for the little carnivores in your house, those cats. Add in renal disease, and it becomes even more significant.

Protein, being a necessary ingredient for everyday living, has degrees of quality. As you might suspect, highly processed sources of protein, like those in byproducts and extruded chunks of food-like particles (kibbles) are vastly different than what the wolf or bobcat eats when he eats prey.

So, here’s another truism, borne out by many years of animal observation in holistic vet circles:

The quality of protein you feed your animal in kidney failure makes a huge difference in how she acts and feels.

Here’s a label excerpt from Hill’s K/D, marketed for cats with kidney disease (I’m showing you the dry version, as I’m fairly certain it’s the bigger seller than the canned):

Chicken, Brewers Rice, Corn Gluten Meal, Whole Grain Wheat, Pork Fat, Brown Rice, Wheat Gluten, Chicken Liver Flavor, Dried Beet Pulp, Flaxseed, Egg Product, Lactic Acid, Calcium Carbonate, Soybean Oil, Potassium Chloride, Choline Chloride, Potassium Citrate, DL-Methionine, Dicalcium Phosphate, vitamins (Vitamin E Supplement, L-Ascorbyl–2-Polyphosphate (source of Vitamin C), Niacin Supplement, Thiamine Mononitrate, Vitamin A Supplement, Calcium Pantothenate, Riboflavin Supplement, Biotin, Vitamin B12 Supplement, Pyridoxine Hydrochloride, Folic Acid, Vitamin D3 Supplement), Taurine, L-Lysine, Calcium Sulfate, minerals (Ferrous Sulfate, Zinc Oxide, Copper Sulfate, Manganous Oxide, Calcium Iodate, Sodium Selenite), Mixed Tocopherols for freshness, L-Tryptophan, Iodized Salt, Natural Flavors , Beta-Carotene

So, in addition to all the high heat and pressure it takes to pop out a piece of kibble (both of which change proteins dramatically), we have

  • spent white rice, left over after the beer brewers have taken their share

  • corn gluten meal, bringing sweets to your carnivore, and setting her up for diabetes later in life

  • gluten in two forms, an inflammatory protein since the 70’s “green revolution” changed it in the name of feeding the planet

Chicken doesn’t sound bad, though, does it? First ingredient. Nice. Or is it?

Here’s the ingredient list from a chicken wing:

  • chicken meat

  • chicken bone

Which food do you think would be more suitable for an animal who has wild genes most closely matching the wolf or bobcat?

Quality matters. Especially so if your animal has kidney trouble.

Feed the Need. The Patient vs The Lab Numbers

I’ve been recommending raw balanced diets for my kidney failure patients for over 25 years now, and I have yet to see anything telling me that’s been harmful. And I’m not alone in this. My holistic vet colleagues do this as well. And see similar results.

If you really want to buy into the low protein idea, it might have some merit at the very end stages of the disease. That occurs when the BUN, a common measure of kidney function, rises above 80 (normal range for the dog: 8.8 – 25.9; normal for the cat: 15.4 - 31.2, Merck Vet Manual).

I’ve not done this, particularly, and I’ve not seen negative effects from it. But it makes sense, and may be worth pursuing if you’re so inclined.

Similarly, animals in the latter stages of CKD have rising phosphorus levels in their blood. Phosphorus in excess hastens kidney disease, so conventional medicine offers phosphorus binding agents to feed cats. All of which have side effects.

Sigh.

News flash: I just brought this question to my homeopathic peers, and there’s an alternative to lower phosphorus that appears to be free of side effects. The B vitamin niacin, in the form of niacinamide, appears to work without the toxic effects of the usual aluminum-based supplements, according to Dr. Lester Mandelker on VIN. Here’s his dose recommendation:

  • Cats and small dogs: 250 mg twice daily

  • Large dogs: 500 mg twice daily

How to give it to cats, the fussy appetite guys? Sara Fox Chapman, DVM, MRCVS, veterinary homeopath who shared the above, says she puts it in the food or mixes the dose in butter and wipes it in/on the cat’s mouth. They tolerate it quite well.

Have any experience with low protein diets in a kidney animal? Or the opposite? Tell us in the comments.

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