Low Protein Dog Foods


Low protein dog foods can be controversial. Even though many veterinarians advise against feeding higher protein diets, recent research appears to support their safety — even for senior dogs with minor kidney issues.

Prescribing Low Protein Dog FoodIn one study of dogs with kidney disease, researchers concluded…

“Results do not support the hypothesis that feeding a high protein diet had a significant adverse effect on renal function”.1

In another study, older dogs were divided into two groups.

One group was fed a low protein diet and the other a high protein diet for the next four years.

“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”.2

Does a High Protein Diet
Cause Kidney Disease?

The Veterinary and Aquatic Services Department of Drs. Foster and Smith addresses what it refers to as a false rumor regarding high protein diets:3

“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.”

Better Quality Protein
Fewer Nitrogen By-Products

So, then, why do so many veterinarians still believe a high protein diet is dangerous to older dogs and kidney health?

“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.”

Restrict Phosphorus
Not Protein

Animals with impaired kidney function are reported to do better by restricting phosphorus intake. However, limiting phosphorus on a preventive basis is not likely to delay the onset of kidney disease or benefit healthy older dogs.4

Drs. Foster and Smith conclude:5

“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.”

Apparently, one of the few justifications for a restricted protein diet is very high urinary nitrogen and elevated urinary protein.6

Or certain types of liver disease, such as hepatic encephalopathy.

The Bottom Line

Due to our respect for a dog’s natural carnivorous bias, we tend to favor dog foods rich in quality meat protein.

However, we also recognize there are medical conditions where a high protein diet can have a negative impact on kidney health.

For this reason, if your dog has been diagnosed with active kidney disease, please be sure to consult with your veterinarian before feeding any food to your pet.


  1. 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
  2. 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
  3. Drs. Foster and Smith, “Are High Protein Diets Harmful to a Dog’s Kidneys?
  4. Thorpe-Vargas S, Cargill JC, Fortify the Food Bowl for the Aging Canine
  5. Drs. Foster and Smith, Ibid
  6. Straus, Mary, Is a Low-Protein Diet Desirable or Necessary for Dogs with Kidney Disease?
  • aquariangt

    not to mention its an inconclusive study :)

  • Pitlove

    Yeah, I find that just seeing one study done on something is really not enough emprical evidence to completely avoid all other treatments or better yet getting to the root of the anxiety. Just like with human anxiety. Masking the problem with meds or in this case a diet, is not really figuring out what is causing the anxiety and fixing it.

    I’ll be interested in hearing about this expo and what was said when you go.

  • aquariangt

    While classical conditioning is the best option here, I would use certain remedies and medications over a low protein diet

  • aquariangt

    I actually know a vet behaviorist that suggests under 21%. I don’t agree. There is 1 study that is used in these recommendations, and it was linked. Very little has been done on the subject, and it’s frustrating that they all hold to this. Not vet behaviorist, but myself and other trainers around here do not agree with this sentiment, and maybe in the next few years a new study will come out about this very subject 😉 However, at clicker expo this year there is a diet and behavior link class. I’ll be front and center at that one

  • Pitlove

    This is certainly interesting, especially the part about aggression. My dog eats a variety of levels of protein. He’s eaten very high (over 40% on a DMB) and is currently eating a food that I consider to be low (about 25% on a DMB). He’s a pitbull that is intact, and while he exhibits dominant behavior, he has never been aggressive on high protein. In fact he’s never been aggressive at all dispite living with 2 other intact male dogs and meeting a variety of dogs, intact and not. He also has no anxiety at all.

    Regardless, best of luck. I do hope that lowering the protein does make a difference for your dog. Science Diet has some of the lowest protein foods I’ve seen. Not a fan of Science Diet, but it could work for your purpose.

  • Crazy4cats

    I have a cat on anxiety meds and I have read about tryptophan helping with the issue. Royal Canin makes a “calm” formula with this ingredient for both cats and dogs. I hope you find something that works.

  • Tamara Marks

    It was recommended to me by my vet behaviorist who said that another famous vet (I’d have to ask her the name) did a study linking high protein diets to aggression and anxiety.

    of dietary protein content and tryptophan supplementation on dominance
    aggression, territorial aggression, and hyperactivity in dogs
    L-tryptophan is a biosynthetic precursor for the neurotransmitter
    serotonin. It has been hypothesized that decreased concentrations of
    this amino acid would lead to reduced formation of serotonin and
    possibly more aggressive responses to stimuli in dogs. Three groups of
    dogs with dominance aggression, territorial aggression, and
    hyperactivity respectively were fed diets differing in protein and
    tryptophan levels. It was found that, for dogs with dominance
    aggression, adding tryptophan to a high-protein diet or changing to a
    low-protein diet may reduce aggression. For dogs with territorial
    aggression, a low-protein diet with added tryptophan may be helpful in
    reducing aggression. The behavior of hyperactive dogs was not influenced
    by dietary protein content or addition of tryptophan.

    View article (PDF, 110 KB)

    Jean S. DeNapoli, Nicholas H. Dodman, Louis Shuster, William M. Rand, Kathy L. Gross

    J Am Vet Med Assoc 2000;217:504-508. August 15, 2000.

  • Pitlove

    I’m also confused, but interested in understanding why you were recommended a low protein food for anxiety. If you want to take another route so that you can continue feeding a more species appropriate amount of animal protein, I’ve used a product called Rescue Remedy for Pets. I used it on a 31 hour car ride down to Louisiana when I moved last year with my 6 year old cat. It was recommended by his old vet, as it was herbal and not a seditive which it was I was most concerned about. It worked very well with no adverse effects. You can find it online or at Whole Foods.