High protein, seniors, kidney disease and CRF

[ldg]

I didn't want to completely hijack this thread, starting here: http://www.thecatsite.com/t/249741/...-to-raw-any-thoughts-suggestions#post_3262974 , but I did want to explore the issue, if anyone else cares to join in....

The discussion started this way...

Speaking of Zoe, who I've pretty much neglected talking about (and am not attempting to transition): today she did eat a bite of sardine and a lick of ground rabbit, but neither was enough to distract her much from her Wellness Core Kitten, which she loves. My vet doesn't like that she eats this, because he says kitten food is too high in protein for an older cat, even though she has no kidney issues. But I've seen nothing to indicate that older cats need less protein, or that reducing protein can *prevent* kidney problems, and in fact the Core Kitten is one of the most balanced of their diets - by Dry Matter percentage it has 50/33/8 protein/fat/carbs. It may not be perfect, and I know it has carageenan, but from what I've been able to tell Wellness Core is otherwise a pretty solid brand, and she's eating it, so my feeling is that I'm not going to worry about the fact that it's labeled for kittens.

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Because you've been looking for scientific studies, you may not have come across this. But your vet is wrong, and you are right! (Trust those instincts!) I think you'll find these very instructive (and you may want to share with your vet? :dk: ) They're written by a veterinary endocrinologist, and cited. Older cats need MORE protein. :nod:

http://endocrinevet.blogspot.no/2011/11/optimal-protein-requirements-for-older.html

http://endocrinevet.blogspot.no/sea...0-05:00&max-results=20&start=14&by-date=false

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Thanks for all of these! The ones about protein needs of older cats don't precisely address the effect of that additional required protein on the kidneys, which I would love to know.

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Glad you put me on the hunt. I actually found a study - one conducted over a year (!) - that measured the impact of high protein on impaired renal function. Not happy that this was measured by surgically removing renal mass, but....

The funny thing is? It was conducted in 1998. What I'm wondering now is... why the focus on low phosphorus in cases of CKD/CRF if it had already been established that high protein did not increase risk of disease in renally impaired cats...

The study is "Protein and calorie effects on progression of induced chronic renal failure in cats." http://www.ncbi.nlm.nih.gov/pubmed/9582959?dopt=Abstract

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It could be that later studies refuted or extended those findings. That is the problem with just looking at one study in isolation particularly such an old one. You really have to examine *all* available research on a topic in order to understand current thinking on it.

This study from 2000 for instance:

http://www.ncbi.nlm.nih.gov/pubmed/10879400


Quote:
Fifty cats with naturally occurring stable chronic renal failure (CRF) were entered into a prospective study on the effect of feeding a veterinary diet restricted in phosphorus and protein with or without an intestinal phosphate binding agent on their survival from initial diagnosis.

Cats fed the veterinary diet survived for longer when compared with those that were not (median survival times of 633 versus 264 days).

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Yep, I assume that's the study JustaCat referred to. :nod:

I would add to your comments, by saying that not only should one study not be used in isolation, it's also just the abstract. :lol3: But it's a starting point, and one to be kept in mind when reading more current work, especially if it's not referenced. My understanding is that the basis for the low phosphorus work comes from studies of rats, though I don't have a citation for that.

 

[ldg]

So I just found this study: http://jn.nutrition.org/content/121/11_Suppl/S140.long

POLZIN, D. J., OSBORNE, C. A., ADAMS, L. G. "Effect of Modified Protein Diets in Dogs and Cats with Chronic Renal Failure: Current Status." J. Nutr. November 1, 1991 vol. 121 no. 11 Suppl S140-S144 It's from 1991, so I expect there are more current studies.

This one again refers primarily to rat studies. But it has this to say about cats (and this is the sum total of the discussion on cats):

In cats, renal function has been found to remain stable for greater than one year after 5/6 reduction in renal mass (30). Proteinuria and glomerular injury were not detected in cats with reduced renal mass fed a 27.6% protein diet. However, cats fed a 51.7% protein diet developed proteinuria and microscopic evidence of glomerular injury. These two diets (footnote 4) differed only in protein and carbohydrate content. The 51.7% protein diet contained (in g/100 g) 36 fat, 8.7 carbohydrate, 0.47 calcium, 0.54 phosphorus, 0.4 potassium and 0.27 sodium. The 27.6% protein diet contained (in g/100 g) 37.1% fat, 30.7 carbohydrate, 0.47 calcium, 0.54 phosphorus, 0.4 potassium and 0.29 sodium. Cats with more severe glomerular lesions had more marked proteinuria. We interpret these observations to indicate that proteinuria and renal structural lesions observed in this study suggest a pattern of declining renal function would ultimately have developed in cats fed the 51.7% protein diet.

Where the citation is

30) ADAMS, L. G., POLZIN, D. J., OSBORNE, C. A. & O'BRIEN, T. D. (1990) Effects of reduced dietary protein in cats with induced chronic renal failure. /. Vet. Intern. Med. 4:125|abs.).

And the footnote is:

4) The diet contained comstarch, chicken fat, casein, sucrose, solka floe, dicalcium phosphate, calcium carbonate, potassium chloride, sodium chloride, mineral mixture, choline, vitamin mixture, d,lmethionine and water.


Interestingly, this article doesn't reference the 1998 piece, "Protein and calorie effects on progression of induced chronic renal failure in cats." Finco DR, Brown SA, Brown CA, Crowell WA, Sunvold G, Cooper TL Am J Vet Res. 1998 May;59(5):575-82. (http://www.ncbi.nlm.nih.gov/pubmed/9582959?dopt=Abstract ) And, unfortunately, the abstract does not indicate how much mass was removed from the kidney. This is pointed out as being of significance in the above piece in the discussion re: CKD and CRF and the macronutrient content of food in dogs.

What they did cite is their own earlier work.
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[mschauer]

Wouldn't they need a time machine to reference the 1998 report since their report was published in 1991?

What exactly is the issue you are exploring? Is it whether or not cats with CRF should be fed restricted protein diet??

 

[ldg]

Of course.... the real question is what causes renal failure. And, as expected, the FelineCRF website has good info: http://www.felinecrf.com/what0.htm

And an interesting discussion (with references) here: http://www.felinecrf.org/nutritional_requirements.htm

 

[mschauer]

From this page:

http://www.felinecrf.com/managd.htm

[font=Arial, Helvetica, sans-serif]There are varying opinions in the veterinary community as to whether low protein food is effective in the management of feline CRF. Some experts believe that any benefit from eating low protein food may be from the lower content of phosphorous contained in the food rather than the low protein itself. [/font][font=Arial, Helvetica, sans-serif]Furthermore, some believe that a low protein diet contributes to weakness and muscle wasting, two very common symptoms in CRF cats.[/font]

They at least seem to believe the issue of whether a low protein diet is beneficial to CRF kitties is unresolved.

This is a fairly recent compilation of current thoughts on the causes of CRF:

http://passthrough.fw-notify.net/static/448544/downloader.js

 

[ldg]

Wouldn't they need a time machine to reference the 1998 report since their report was published in 1991?

What exactly is the issue you are exploring? Is it whether or not cats with CRF should be fed restricted protein diet??

:lol3: Yes, they would have needed a time machine. :doh3:

Two things:

1) what is the impact of high protein diets on the kidneys of older cats (can it contribute to renal failure?) (This thread got me wondering - I mean - why suggest the k/d diet in the absence of renal compromise? :dk: It seems nuts to me, but I've never researched it in any way http://www.thecatsite.com/t/249867/all-the-vets-i-have-been-to-said-senior-cats-should-eat-kd ).

2) The question you listed - should cats with CKD or CRF be fed restricted protein diets?


For instance, in the study that you posted (that is typically referenced as re: reduced protein for CKD/CRF), the FelineCRF website has this to say:

There are also some studies into the use of prescription kidney diets, which of course are not only low protein. In Survival of cats with naturally occurring chronic renal failure: effect of dietary management (2000) Elliott J, Rawlings JM, Markwell PJ, Barber PJ Journal of Small Animal Practice 41 pp235-42, 29 cats were fed a low protein, low phosphorus prescription diet, while a further 21 cats did not eat the prescription diet. Some of the cats (presumably in both groups) were also given phosphorus binders. The cats fed the prescription diet survived longer than the other cats, but it is not clear whether this was due to the reduction in phosphorus intake rather than the reduction in protein intake.

Now.... on a raw diet, the only way to reduce phosphorus would be to use a phosphorus binder, as the phosphorus comes with the protein.... or to increase the amount of fat or carbs vs protein... :dk:

 

[ldg]

This is a fairly recent compilation of current thoughts on the causes of CRF:

http://passthrough.fw-notify.net/static/448544/downloader.js

The link isn't working for me....

 

[mschauer]

This is a fairly recent compilation of current thoughts on the causes of CRF:

http://passthrough.fw-notify.net/static/448544/downloader.js

The link isn't working for me....

Hmm. It's a PDF. Try Googling "Epidemiology of Feline Chronic Kidney Disease".

Or try this:

http://www.banfield.com/Banfield/files/9e/9e7f2a34-c7e5-4504-b04a-2524b8331c42.pdf

 

[ldg]

Thanks, got it.

 

[ldg]

Hunh. Based on the Banfield review, it seems like there really hasn't been much research done.

 

[carolina]

Hunh. Based on the Banfield review, it seems like there really hasn't been much research done.

That's what I got from it.... The only conclusion that they have, is that AGE is a factor.... everything else is inconclusive.

 

[sugarcatmom]

Now.... on a raw diet, the only way to reduce phosphorus would be to use a phosphorus binder, as the phosphorus comes with the protein.... or to increase the amount of fat or carbs vs protein...

Just chiming in quickly on this: another good way to reduce the phosphorus in a raw diet is to minimize or eliminate the bone content and feed a phosphorus-free calcium supplement instead. Bone contains quite a substantial amount of phosphorus. My CKD kitty, Aztec, eats lots of commercial raw venison or buffalo, a brand that doesn't contain bone or bone meal, and has DM phosphorus levels almost as low as the prescription renal diets. When you add in a calcium supp, that takes it even lower. He's already exceeded that 633 day median survival time of those cats in the study fed the "veterinary diet" by many months. (Would love to know what the "other diet" was they were feeding those poor cats that only lived an average of 264 days. 

 I'm sure it was really great if it made K/D look good. 

)

 

[whollycat]

I've been pulling together some info I've collected. This might be a little long, but hoping it is of some value. Keep in mind that I had a CKD bubby, Tuffy (Abby's brother), so although I wasn't able to implement all of what I'm adding here, I did go with better quality meat-based canned foods for Tuffy. Only after Tuffy crossed over did I discover feeding raw. In my opinion, a balanced raw diet is an optimal diet for CKD kitties, and I would not hesitate to modify our raw diet for a CKD kitty (keeping in mind the 3 items I listed below--there are more, but I only included these for now).

Another case in point is my boy Abby, who is now a very spry 16-years-old, non-CKD, raw fed since end of 2005, early 2006. Everyone who sees him does not believe that he is 16--they guess half that age. His coat is a glossy strawberry blond, he's agile and loves to play, and he is at a good weight (he was overweight before we switched to raw).

Note that this is only a little overview of my thoughts and thinking on the subject of CKD and/or older kitties:

First off, a belief that I have NOT held for years--and looking at the physiology and biological processes that are unique to kitties--while and since, caring for my Tuffy is: “A low-protein diet will aid in reducing the residue from protein metabolism that the kidneys need to filter.” <== I find this statement held by many (I know, it is controversial to this day) to suggest a low protein diet for a carnivore and a CKD kitty to be somewhat misleading (maybe that's not the right word, but might make sense as you read further

). Here's why:

#1 Protein. A diet of high quality meat protein will have less “residue” due to its high bioavailability for cats. The key here is the quality of the meat, perhaps including the processing that it goes through. Also, in commercial foods, the amount of protein most likely is NOT from only the meat content. It can also include protein amounts in grains, veggies, and fruits. Until pet food companies are required to list exactly where the total protein percentage in the food comes from, it is a guessing game. With a raw diet you KNOW what is in the food and where the protein is coming from--real meat. In the latter stages of CKD, adding cooked egg whites (never raw) will provide a quality, low-residue, bioavailable protein to their diet. Kitties are carnivores and depriving them of this essential part of their diet sets them up for muscle wasting, weight loss, and other detrimental processes.

#2 Fat. Specifically animal fat in higher amounts in a CKD kitty’s diet will provide a source of low residue, highly bioavailable nutrition. Fat doesn’t contribute to waste products that must be filtered by the kidneys. A kitty without CKD would gain weight on a higher fat diet, but a CKD kitty has the opposite problem—keeping weight on. Adding more fat helps them maintain a healthier weight. Fat can be a good enticement to get CKD kitties to eat, and fully usable by their little bodies.

#3 Phosphorus. Kitties with CKD usually develop high levels of phosphorus in their blood (hyperphosphataemia). Because of this, it is the only component of the diet that needs to be restricted because CKD kitties can no longer efficiently excrete excess phosphorus. Phosphorus can be controlled with phosphate binders and feeding lower phosphorus containing meats. In the latter stages of CKD, you can use cooked egg whites to add quality, bioavailable, low-residue, negligible (almost no)-phosphorus containing protein to a CKD kitty’s diet.

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http://www.southpaws.com/news/99-2-nutrition-CF.htm

By Dr. Tina Kalkstein [article is buried somewhere on the above site now—I had copied the text below and saved it in my files]

Rationale against low protein diets:

All body protein is functional protein (muscle, organs, and cells, circulating proteins such as albumin and globulins).

There are no stores of protein in the body as there are for fat in obvious places or carbohydrates in the liver or muscles.

Therefore any excess protein during a positive nitrogen balance is eliminated from the body. Many patients are initially diagnosed with CRF when already in a protein malnourished state and negative nitrogen balance (significant weight loss and poor body condition, poor haircoat, hypoalbuminemia).

The clinical signs of protein malnutrition suggest that catabolism has been chronic, sustained for possibly months before these signs become detectable.

This state develops because protein depletion forces body proteins to be catabolized to meet regular nutritional needs. Acidosis also causes the breakdown of body proteins.

Catabolism of endogenous proteins for any reason will increase the level of azotemia (remember: protein is protein no matter where it comes from-the exogenous food we feed or endogenous body mass that is catabolized).

By forcing all CRF patients to eat a low protein diet, protein malnutrition may be induced or perpetuated if the diet does not meet the body's nutritional needs and/or the patient finds the diet unpalatable and chooses not to eat enough or any of the diet. Also remember, limiting protein intake in CRF is not reno-protective (i.e. this will not prevent progression of renal damage).

It is also worth mentioning that low protein diets will not delay or prevent the onset of CRF in healthy older animals. This means that our more senior patients do not need a low protein diet or one specifically designed for the older pet. A regular maintenance diet is fine for most older healthy cats [and dogs].

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Bioavailability of meat protein is important. I touched on this above, but found this interesting (my underlining added):

A carnivore's optimum diet must be concentrated, highly digestible, and low in residue. (http://maxshouse.com/feline_nutrition.htm) Protein digestibility in pet foods is about 80 percent for dry foods, 85 percent for semimoist and canned foods containing large amounts of cereal grains, and 90 percent for canned diets with meat as the primary protein source. Digestibility is influenced both by the source of the protein and by how it is processed. Protein in cat foods comes from both animal and plant sources. Animal protein is generally more expensive and often of higher quality than plant protein.  The composition of canned foods allows the use of protein and fat sources of higher biological value than can be used in dry food.  A recent survey (Morris, James G. and Quinton R. Rogers. 1994. Assessment of the nutritional adequacy of pet foods through the life cycle. Journal of Nutrition 124:252OS-2534S), compared a well-known canned food with the leading dry food, both of which claim to provide "balanced" nutrition.

The digestibility claim of the canned food was approximately 90%, while the digestibility of the dry food was rated at 80%.  The biological value of the protein content (in other words, how useful the protein is to the animal) was given as 70% for the canned food and 60% for the dry. Net utilization (the amount of food used by the animal in relation to the amount provided) can be calculated by multiplying digestibility by biological value. The results: 68 % net utilization for the canned  food and 48% for the dry. This means a cat would have to eat nearly twice the volume of dry food to achieve the net utilization that higher, more digestible sources of nutrients, found in canned food, would provide.  All those excess waste products must be filtered from the blood placing an extra workload on the kidneys.   This may explain the high prevalence of chronic renal failure in middle-aged cats.

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Just my thoughts to add to the conversation.

ETA: It must be pointed out that almost (all?) studies regarding CKD over the years have been done by feeding non-raw diets (as in commercial foods, including vet diets), and most don't tell you exactly what was fed.

 

[carolina]

Now.... on a raw diet, the only way to reduce phosphorus would be to use a phosphorus binder, as the phosphorus comes with the protein.... or to increase the amount of fat or carbs vs protein... :dk:

Just chiming in quickly on this: another good way to reduce the phosphorus in a raw diet is to minimize or eliminate the bone content and feed a phosphorus-free calcium supplement instead. Bone contains quite a substantial amount of phosphorus. My CKD kitty, Aztec, eats lots of commercial raw venison or buffalo, a brand that doesn't contain bone or bone meal, and has DM phosphorus levels almost as low as the prescription renal diets. When you add in a calcium supp, that takes it even lower. He's already exceeded that 633 day median survival time of those cats in the study fed the "veterinary diet" by many months. (Would love to know what the "other diet" was they were feeding those poor cats that only lived an average of 264 days. :frown2:  I'm sure it was really great if it made K/D look good. :uuh: )

I hear eggshell powder works as a good phosphorous binder (that's Calcium Carbonate).... I wasn't aware of using it instead of bone altogether- Sugarcatmom, is that what you use?
I have also seen quite a few CRF kitties parents substituting some of the meat (a small percentage, not too much) for cooked egg whites. They are a good source of protein, but very low in phosphorous. That helps keeping that levels down without compromising the protein levels :nod: So.... that's another option aside from fat and carbs.....

 

[carolina]

Should read your long post Whollycat :lol3:

 

[whollycat]

Should read your long post Whollycat

I forewarned that it was long, Carolina--but the text is pretty big so maybe not as long as it looks.

Do let me know what you think because I value your opinion.

ETA: Oh...duh...bet you mean because I mentioned egg whites?

 

[carolina]

I forewarned that it was long, Carolina--but the text is pretty big so maybe not as long as it looks. Do let me know what you think because I value your opinion. :rub:

ETA: Oh...duh...bet you mean because I mentioned egg whites? :doh3:

but the rest too :nod:

 

[ldg]

Jules, THANK YOU for that!

And Sugarcatmom, GREAT point about the bone and phosphorus - another THANK YOU!

 

[sugarcatmom]

#1 Protein. A diet of high quality meat protein will have less “residue” due to its high bioavailability for cats. The key here is the quality of the meat, perhaps including the processing that it goes through. Also, in commercial foods, the amount of protein most likely is NOT from only the meat content. It can also include protein amounts in grains, veggies, and fruits. 

Dr. Karen Becker talks about this very issue in another one of her great videos on the topic of pet food: 

The Nutrient Your Pet Needs More Of As They Age

Not All Protein is Created Equal

Protein quality is extremely variable. There are highly assimilable and digestible proteins (proteins your pet’s body can easily absorb and make use of), and there are proteins that are wholly indigestible. For example beaks, feet, hides, tails and snouts are 100 percent protein, but all 100 percent is indigestible.

All protein has a biologic value, which is its usable amino acid content. Eggs have the highest biologic value at 100 percent. Fish is a close second at 92 percent. Feathers, as you might guess, have zero biologic value. They are all protein, but they are neither digestible nor assimilable.

Now there are some foods high in protein that are not species-appropriate for dogs and cats. Soy is a good example, with a biologic value of 67 percent. Many popular pet foods contain soy as a protein source, as well as corn. This is an inexpensive way for pet food manufacturers to increase protein content on the guaranteed analysis printed on the label.

But because soy and corn are not species-appropriate, I don’t recommend you feed pet foods that contain it.

Unfortunately, digestion and assimilation are not measured for dog and cat foods, so manufacturers can include other types of protein that have no biologic value for the species of animal eating it (this is also why melamine was added to pet foods that killed thousands of animals). You can be fooled into thinking you’re feeding a higher-protein food, when the reality is the protein isn’t biologically appropriate for your pet.

Quote:

ETA: It must be pointed out that almost (all?) studies regarding CKD over the years have been done by feeding non-raw diets (as in commercial foods, including vet diets), and most don't tell you exactly what was  fed.

Bingo! In fact most of those studies likely use commercial DRY diets with high amounts of poor quality plant protein, which can indeed contribute to renal damage. Lessening that amount of poor quality protein by feeding one of the prescription foods may very well help a kidney cat in comparison. But if those same cats were actually fed a species appropriate FRESH raw diet instead.....well let's just say Hill's/Purina/Royal-Canin et al don't want you to know how much better off they'd be.

More from Dr. Becker:

Rendered Pet Food – The Worst of the Worst

Asking a dog’s or cat’s liver and kidneys to process low-quality, indigestible protein over a long period of time is exactly how protein in pet food got a bad rap.

In the 1940s and 1950s, there were really no high quality commercial pet foods on the market. Formulas at that time contained 100 percent run-off or rendered byproducts from the human food industry.

Pet food companies took all the pieces and parts left over at slaughterhouses, mixed them with discarded vegetables and grains not fit for human consumption, added a synthetic vitamin-mineral supplement, and called it pet food.

While there was a fair amount of protein in pet food back then, the quality was just terrible. Because the protein was so difficult for dogs and cats to digest, kidney and liver function suffered.

That’s why veterinarians around the mid-century mark started recommending lower protein senior pet foods. Senior formulas came into being because of the terrible quality of dog and cat foods on the market.

That’s why I strongly recommend if you’re feeding a rendered pet food formula  – food that contains protein that is not digestible or assimilable – that you reduce the amount of protein you’re feeding. Your pet’s organs can’t process a steady diet of terrible quality protein.

 

[sugarcatmom]

I hear eggshell powder works as a good phosphorous binder (that's Calcium Carbonate).... I wasn't aware of using it instead of bone altogether- Sugarcatmom, is that what you use?
 

I do use some calcium carbonate and also this product from Easy Vitamins & Minerals: http://www.EZVitamins.com/more_calcium.html

I have also seen quite a few CRF kitties parents substituting some of the meat (a small percentage, not too much) for cooked egg whites. 

I sure wish Aztec liked egg whites but even a hint of a whiff of them in his food and he runs away in horror.