The Lie About Low Protein Dog Food:
There is a commonly-known myth in the dog food industry about protein content in dog food. The myth claims that high-protein diets are dangerous to dogs and especially dangerous to older dogs and can cause kidney disease or in severe cases, complete kidney failure. This is simply not true.
In one study, the research concluded:
Results do not support the hypothesis that feeding a high protein diet had a significant adverse effect on renal function.
In another study that involved two groups of older dogs, one group was fed a low protein diet while the other group was fed a high protein diet for the following 4 years. The conclusion of the study was:
Results of this study indicated there were no adverse effects from the high protein diet and mortality (death rate) was actually higher in the low protein group.
So the question then remains, does high protein content in dog food diets cause kidney disease? The Veterinary and Aquatic Services Department of Drs. Foster and Smith concluded that the myth that high-protein content dog food is a direct cause for kidney disease is false:
This rumor is false. High protein pet foods are NOT harmful to a normal animal’s kidneys. As an animal’s body digests and metabolizes protein, nitrogen is released as a by-product. The excess nitrogen is excreted by the kidneys. A high protein diet produces more nitrogen by-products and the kidneys simply excrete the nitrogen in the urine. While you may think this would ‘overwork’ the kidneys and lead to possible kidney damage, this is not true. The kidney’s filtering capabilities are so great that even one kidney is sufficient to sustain a normal life. There are many pets – and humans – living perfectly healthy lives with just one kidney.
Then you may still ask why so many veterinarians still believe that a high-protein diet is harmful to older dogs and dangerous to kidney health? Drs. Foster and Smith continues:
The myth that high protein diets are harmful to kidneys probably started because, in the past, patients with kidney disease were commonly placed on low protein (and thus low nitrogen) diets. Now, we often put them on a diet that is not necessarily very low in protein, but contains protein that is more digestible so there are fewer nitrogen by-products. These diet changes are made merely because damaged kidneys may not be able to handle the excess nitrogen efficiently. In pets with existing kidney problems, nitrogen can become too high in the bloodstream, which can harm other tissues.
So why do we need to worry about lower protein diets at all? Drs. Foster and Smith concludes:
Unless your veterinarian has told you your pet has a kidney problem and it is severe enough to adjust the protein intake, you can feed your pet a high protein diet without worrying about ‘damaging’ or ‘stressing’ your pet’s kidneys.
Ok, so do we avoid low protein diets then?
Well, yes, and no. If your dog is living a normal lifestyle and no medical conditions exist that could justify the restriction of his protein intake, you may actually expose him to malnutrition when fed a lower protein diet.
However, according to a study conducted after testing the kidney function, creatinine (a blood marker for kidney function), body condition and survival time of dogs fed a low protein diet (16%) and those fed a normal diet (22.5% protein) shared by Dr. Ken Tudor, this is what was found:
What they found was no significant difference in kidney function, blood creatinine levels or survival time between the two groups. As expected the body condition scores were greater for the normal protein group as they maintained more muscle mass. The main determinant of survival time was the level of kidney dysfunction at the time of diagnosis, not the diet.
The study concluded:
This study also suggests that phosphorus control is more important than dietary protein in kidney patients.
The Bottom Line…
Thus, the bottom line is, if you have a healthy dog with normal kidney function and normal creatinine levels, you will not prolong the life of your dog by feeding him a low protein diet, nor will you cause any damage to your dog’s kidneys by feeding him a high protein diet. In fact, you may expose him to malnutrition if he’s perfectly healthy and you feed him a lower protein diet.
With that said, dogs with existing kidney disfunction may need to be fed a lower protein diet in order to restrict the phosphorus intake, which is essential for kidney patients according to Dr. Jean Hofve:
The real culprit is not protein but phosphorus, which combines with calcium and gets deposited in the kidneys, causing further damage. Meat contains a lot of phosphorus, so the easiest way to restrict phosphorus is to restrict meat protein. Decreasing phosphorus intake (by restricting protein) can help some pets feel better, so it may be worth a try if the symptoms are a problem.
Low protein diets are prescribed by your veterinarian when there are serious medical conditions present which may include:
- Acute kidney failure
- Chronic kidney failure
- Congenital kidney disease
- Genetic kidney problems
- Kidney failure due to Lyme and other parasite born diseases
- Congestive heart failure
- Tendency for urinary stones
The Ultimate Guide of Low Protein Diets for Dogs
We’ve put in the hard work for you and sourced the best low protein diets available on the market. This comparison table will make your life a lot easier to order your favorite prescribed low protein diet directly online.
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- Bovee, KC, Influence of Dietary Protein on Renal Function in Dogs, Waltham International Symposium on Nutrition of Small Companion Animals, University of California, Davis, CA 95616, on September 4–8, 1990
- Finco DR, Brown SA, Crowell WA, et al, Effects of aging and dietary protein intake on uninephrectomized geriatric dogs, Am J Vet Res 1994; 55:1282
- Are high protein diets harmful to a dog’s kidneys? by Veterinary & Aquatic Services Department, Drs. Foster & Smith
- Dietary Protein and Kidney Disease by Dr. Ken Tudor
- Kidney Disease in Cats and Dogs by Dr. Jean Hofve