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Protein Malnutrition in CKD Dogs

One mistake I observe dog owners make is to forget that dogs are dogs and they require meat in their diet.

We are told that protein is hard for the kidneys to process, but what we have to remember at the same time is that protein malnutrition can also kill a dog. 

I’ve recently created a course to educate dog owners about how Traditional Chinese Medicine views Canine Kidney Disease (CKD).

You can enroll in the course by clicking on the photo below.

I’m also sharing an excerpt from one of the modules in the course to answer the question about what to feed dogs with CKD and what studies we know to date:

What About The Studies?

The initial studies that laid out the first dietary guidelines took eighty-six rats and removed 75% of their kidneys. 

Even when this was done, the study states: “We cannot induce in animals the exact structural renal changes that we find in the initial stage of glomerular nephritis.” (Addis, p. 272). 

We have to keep this in mind because kidneys that have been reduced in size due to operation do not function entirely the same way as kidneys that reduce in function naturally. 

How each set of kidneys functions in both scenarios is different. 

The study further states that each stage of glomerular nephritis presents special problems. The practical application of this is that when we are looking as to what to feed the dog (which is still different from the rat) and each stage should be personalized to that dog. 

To quickly jump to a low-protein diet too early can compound problems and worsen things. 

Too little protein can be insufficient for body maintenance. 

Drinking Sugar For 24 Hours

It was interesting to note that the only way to get the calories into these rats was to give them dextrose water. If you lower protein to the point that they do not have energy from food, then it came from sugar water. 

When one set of the rats was given no protein, while their kidney numbers looked good, the bodies of the rats did not. They were “emaciated and depleted” (Addis, p. 277).

In plain English, what this study is saying, while the test results looked good, the rats were so weak they were skinny and could not even have enough energy to feed themselves.  

“These rat experiments were planned to reproduce as nearly as possible the conditions of glomerular nephritis but they are of course, far removed from what truly happens in each dog.” (Addis, p. 277)

Rats and Dogs Are Not The Same. Let’s Look At All Six Studies

Low protein diets were found to extend the life of rats in studies between 1919 and 1989. There are a few things to note:

  1. These diets were also low energy (as in not enough food/kcal)
  2. These diets were highly unpalatable 
  3. The low energy intake, rather than the low protein content is what slowed the rat’s growth – this retarded progressive renal failure
  4. Rats… do not stop growing and they live till they are about 3 years old.
  5. How rats eat are different. They eat 24 hours a day nibbling. And the renal load is different in a rat vs. a dog that eats, once, or twice a day. 
  6. The first study on dogs was related to renal senescence rather than to clinical failure. No change between the dogs fed 3 different levels of protein but after 2 years, those dogs fed the lowest (16%) fared the worse. These studies were done 1979 and then 1986) and the efficacy of prescription diets was questioned. 

    “No significant ultrastructural differences were found in glomeruli among the three diet groups. These results do not support the hypothesis that high protein feeding had a significant adverse effect on either renal function of morphology in dogs with 75% nephrectomy.” (Bovee)
  7. A second study then introduced a lower protein diet – at 8% . The results were similar because certain amino acids like arginine were too low. 

    “Uremic dogs have the capacity to adapt to a wide range of dietary protein and solute changes. The protein quality of 1 special dietary product was not superior to ordinary commercial foods. A nutritional feature associated with the reduced ability of both special dietary products to maintain renal function was reduced intake of essential amino acids, especially arginine. These findings raise doubt about the safety and efficacy of 2 special dietary products intended for dogs with chronic renal failure, which contain moderately reduced (18%) and somewhat lower (8%) protein.” (Bovee)
  8. A third study then compared the responses of the dog before partial nephrectomy. The dogs fed 7% protein developed protein deficiency. (Polzin and others 1982) and the dogs fed 14% protein los less bodyweight than those fed 44% or 7% protein.
  9. A fourth study was done – and they learned that protein restriction beyond 1.9g/kg bodyweight daily should not be done unless necessary to control debilitating clinical signs of uremia.  No information was given on what those clinical signs would be except bodyweight.  (Polzin and others 1991)

    Restricting protein intake to less than 1–9 g protein/kg bodyweight/day further reduced retention of nitrogenous waste products as measured by serum urea nitrogen concentrations, but at the expense of adequate protein nutrition. Diets providing less than 1–9 g protein/kg bodyweight/day promoted protein malnutrition characterised by hypoproteinaemia and hypoalbuminaemia in both normal dogs and dogs with renal failure. Serum protein concentrations were similar in normal and renal failure dogs, suggesting that, under the conditions of this study, normal and renal failure dogs may have similar protein requirements. Progressive dietary protein/phosphate restriction improved but did not normalise phosphate balance in renal failure dogs. (Polzin and others 1991)
  10. In a fifth study, a phosphate binder was used. Uremic signs were shown in dogs fed high protein (50% DM) and low protein (16%) but conditions stayed the same in the dogs fed moderate protein 24% DM. There were two mortalities in dogs fed the low protein diet.  (Finco)
  11. In a sixth study, hyperfiltration was worse in the dogs fed a low protein – 16% diet vs. those fed 30%

The Remaining Kidney Grows When Fed Higher Protein Diets

Compensatory growth of the renal remnant was studied following 85 to 90% partial nephrectomy. Two diets were studied. One at 26% and the other at 13%. They fed the dogs each diet for 7 months and then switched them. Growth was larger in the dogs fed the higher protein diet. (Remember, protein builds protein). After 14 months the renal reserve was measured and there was an immediate advantage from the dogs fed the diet with 26% protein and residual benefit from the initial allocation to that diet. 

What About Clinical Trials?

There have been four trials of prescription renal diets on naturally occurring kidney disease. 

  1. These dogs lived with their owners. And they had to come back every two weeks for an evaluation. The owners fed the dogs the food. The dogs fed very low protein (7%) didn’t do well. The diets were very poorly accepted, induced metabolic acidosis and hypoalbuminemia, and could not sustain life. The authors claimed the dogs fed the diets with 14% protein did the best, but when the data is reviewed between those fed 14% and those fed 44%, there were no significant differences between these dogs. 
  2. In the second trial, nine dogs were studied with mild to moderate renal failure. Two diets were studied with differing protein, phosphorus, and sodium levels. Even though the study involved different diets, the people who designed the study said the emphasis was to look at the homeostatic processes. The author’s conclusion was serious undesirable and unexplainable consequences (hypertension, hypercholesterolemia, and possible hypothyroidism) were greater and were not worth the benefits they were looking for (mitigation of azotaemia, phosphataemia, anemia, and hyperparathyroidism). 
  3. In a third trial, two different diets were studied. One was canned, the other was homemade. They had the same protein level (20%), but the phosphorus and sodium levels were different. Sixty dogs were studied for 28 weeks. Thirty-two were fed the canned product and twenty-eight were fed the homemade diet. Eight dogs died when fed the canned product. And six dogs died when fed the homemade diet, most in four weeks and all by the eighth week. Collectively the study found that dogs were stabilized, and the dogs were fed a moderate protein, low phosphorus diet. 
  4. In the fourth trial, they studied two low-protein diets and had one high-protein phosphorus diet as the control. They reported that the dogs on the two low-protein diets did the best but….
    • a) They did not report mortality rates.
    • b) They did not study moderate protein diets like other trials and studies had in the past. 
    • c) They did not mention any of the disadvantages seen in all of the other previous studies and trials from dogs fed a low protein diet

Feed The Dog First, Then The Kidneys

In deciding how to feed a dog that has CKD, we should remember:

  • To feed the species. Dogs still need meat (protein).
    • A “species appropriate” diet is a diet that animal has evolved to eat. For example panda bears eat bamboo. Feeding them bamboo is appropriate to the species. Dogs are facultive carnivores. That means as a species, they are supposed to be fed mostly a meat diet, with some non animal food.
  • To understand the root cause. Because if we feed a high-fat renal diet to a dog with pancreatitis, this will complicate things. Or if we feed a kibble diet to a dog that has diabetes, this is too much carbs, and their body may go into a tailspin.
  • Protein is needed for tissue repair. Denying the dog protein could lead to other problems such as muscle wasting, fatigue, and more. 
  • Feed enough calories. Oftentimes, I observe dog parents switch to a home-cooked diet using a base mix and limit the calories in the protein in the early stage, and not calculate the amount of energy a dog needs to survive, and the dog suffers because they are underfed and subsequently drop weight and waste away. 
  • Only look at protein level when the dog has reached a critical point based on clinical status, degree of azotaemia and hyperphosphataemia, glomerular filtration, and parathyroid hormone, depending on the clinic’s resources. That said, there hasn’t yet been an agreement globally on what this “critical point” is. 

So What Do You Need to Know?

  1. Know how much energy your dog needs to live each day. 
  2. Know how much protein your dog needs in the stage they are in. 

This is the time to learn dog nutrition so that you can feed your dog enough of the right food. 

If you need help with homemade recipes, book a call with me HERE.

I wish you and your dogs good health.


Addis, T. (1948) Glomerular Nephritis: Diagnosis and Treatment. MacMillan, New York

Bovee, K. C., Kronfeld, D. S. Rambers, G. F. & Goldschmidt, M. (1979) Long term measurement of renal function in partially nephrectomized dogs fed 56, 27, or 19 percent protein. Investigative Nephrology 16, 378-384

Bovee, K. C. & Kronfeld, D. S. (1981) Reduction of renal hemodynamics in uremic dogs fed reduced protein diets. Journal of the American Animal Hospital Association. 17, 277-284.

Finco, D. R. Crowell, W. A. & Barsanti, J. A. (1985) Effects of three diets on dogs with induced renal failure. In: Current Veterinary Therapy X. Ed R. W. Kirk, W. B. Saunders, Philadelphia. pp 1198-1201

Polzin, D. J. & Osborne, C. A., (1986) Current progress in slow progression of canine and feline chronic renal failure. Companion Animal Practice 3, 52-62

Polzin, D. J. & Osborne, C .A., Hayden, D. W. & Stevens, J. B. (1981) Experimental evaluation of reduced protein diets in the management of primary polyuric renal failure: preliminary findings and their clinical significance. Minnesota Veterinarian 21, 16-29

Polzin, D. J. & Osborne, C. A., Stevens, J. B. & Hayden, D. W. (1982) Influence of modified protein diets on electrolyte, acid-base, and divalent ion balance in dogs with experimentally induced chronic renal failure. American Journal of Veterinary Research 43, 1978-1986

Polzin, D. J. & Osborne, C. A., J. B. & Hayden, D. W. (1983) Influence of modified protein diets on the nutritional status of dogs in induced chronic renal failure. American Journal of Veterinary Research 44, 1694-1702

Polzin, D. J. & Osborne, C. A., J. B. & Hayden, D. W. (1984) Influence of reduced protein diets on morbidity, mortality and renal function in dogs with induced chronic renal failure. American Journal of Veterinary Research 45, 506-517

Polzin, D. J. & Osborne, C. A., & Lulich, J. P. (1991) Effects of dietary protein/phosphate restriction in normal dogs and dogs with chronic renal failure. Journal of Small Animal Practice 32, 289-295

Author Biography

Hannah Zulueta obtained her Certificate in Canine Nutrition from CASI Institute. She is also studying for her Doctorate in Acupuncture, Traditional Chinese Medicine, and Herbalism from the esteemed Pacific College of Health and Medicine.

She resides in San Diego with her three dogs, Maggie, Orbit, and Mr. Higgins.

She is available for one on one consultations. Additionally, you can find her sharing free content on Instagram.

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