With so many options out there, how can we know what’s the best for our furry family members? It’s no secret that high protein dog food is a huge trend, but that led us to question: is there such a thing as too much protein? If so, how much is too much? We asked our pet nutrition specialist to do a deep dive into the research to tell us more.

So bare with us, this one gets a little science-heavy – but we think it’s worth it! As a pet parent, we want you to be empowered with as much knowledge as possible to help you navigate the challenge of finding your bff the best diet for them.

First off we know that sometimes the best option isn’t so clear. This is especially true when it comes to the amount of protein in pet food!

What we know:

Commercial dog foods have different amounts of crude protein, ranging from 18% to over 60%! What may surprise you is that the ideal range of protein required for a healthy adult dog hasn’t been determined.

The Association of American Feed Control Officials (AAFCO) and the European pet food industry (FEDIAF) recommend a minimum crude protein concentration of 18.0% on a dry matter (DM) basis for adult maintenance dog food ^1-2. These associations have minimums, but there is no clear “best” concentrations or even an upper limit suggested. So, how do pet owners choose what’s best for their dogs?

With no concrete answers from associations, let’s look at some factors and how protein levels can affect our dog.

The Canine Microbiome

You may have heard of the microbiome before. Well, like you or I, our dogs also have a gut microbiome. This wonderful microscopic world inside us is known to influence our health but to what extent remains to be established. However, what we do know is that it does have some degree of influence. Studies have investigated the effects of high protein levels on the canine microbiome (Yay!), the bad news is not a lot of studies have looked into a range of protein levels. This makes it hard to gain any concrete answers.

But, here’s what we do know:

Studies looking into high protein levels found that high dietary protein leads to increases in fecal pH along with metabolites like branched-chain fatty acids (BCFAs) and indole sulfates in dogs ^3–7.

This indicates that a higher amount of protein in the diet leads to increased protein available to the microorganisms found in microbiomes.

Well, what the heck does this mean?

This means that higher concentrations of protein also lead to more circulating urea in the body ⁸. Urea is an end product produced when protein is broken down in the body. It’s found in urine, blood, bile, milk and even sweat. Increases in uremic toxins can come from protein fermentation in the colon⁹. Some of these toxins are indole sulfates and p-cresol: and neither are great for health ¹⁰.

Eating more protein is also associated with a higher fecal pH because more of it must be broken down by the gut microbiome.

So studies indicate that feeding dogs a high amount of protein can lead to a shift in gut bacteria to favour protein breakdown and a higher fecal pH; both of which are associated with higher levels of metabolites linked to inflammation and kidney dysfunction ⁹. That said: whether or not this is ultimately harmful to dogs needs to be further investigated. Unfortunately, most of the current research available has been done in other mammals so it’s difficult to make a firm conclusion when it comes to our furry best friends. One study also found that lean dogs may be more resilient to changes in dietary protein levels than obese dogs ¹³.

The long-term health effects of these changes in the microbiome should be further researched before we can draw fully formed conclusions.

So, what is the right protein content for your dog?

It is likely not in the range of over 60% or even 40% DM. However, this question could be more complicated. It also depends on your dog’s age, current weight, health and reproductive status (check out How to Choose the Best High-Quality Dog Food).

Sometimes there are benefits to high-protein diets. For instance, if your dog is overweight, they could likely be consuming a weight management diet that is higher in protein and higher in fibre. This diet can be useful for dogs to lose weight due to the high fibre content which makes your dog feel full and satiated eating less. They will not lose muscle mass because of the high protein content.

What protein content is the best for your dog also likely depends on their size.

Are they miniature, small, medium, big or a giant breed?
Recent studies investigating some essential amino acids have shown different requirements for different dog sizes ^14–16. Therefore, the right protein content likely varies due to these factors as well. Nonetheless, current research, as well as current guidelines, do not state the “right” protein content for any dog as of right now.

More Protein Isn’t Necessarily Better For Your Pupper or for the Planet

We know the minimum requirement for protein is 18% DM.
We also know the research points to a shift in the gut microbiome from too much protein linked to inflammation and kidney dysfunction ⁹. So, choosing something in the middle of the road is likely your best starting point. And of course, we recommend monitoring your dog’s health and consulting their vet whenever there’s a concern.

From a health perspective, more research is needed to learn the optimal amount of protein for your dog based on these factors. However, with the growing trend of high protein diets, we think it’s important to ask ourselves: is all that protein really necessary, or is it just wasteful? We know the environmental cost of the production of animal protein is a high one and based on the current body of research, most dog foods offer protein levels well above nutrient requirements. With more animal protein comes more damage to the planet so we recommend focusing on nutrients not just ingredients when it comes to choosing your dogs’ food.

Focusing on Nutrients, Not Ingredients, Is Key

Undigested protein is far from ideal. It’s not utilized through the digestive system and is just excreted in feces which can produce a more unpleasant smell. Excess protein can also increase nitrogen excretion in urine without any benefit to your pet (and kill your lawn!). This excess nitrogen elimination can negatively impact our environment because of increased acidification and eutrophication of soil. One of the most important considerations is the digestibility of the amino acids being provided by the protein sources. Dogs, like humans, require specific nutrients, not ingredients. These nutrients can be reached with a variety of different ingredient sources, including animal products, novel proteins, grains, pulses, etc.

We aim to use accurate protein contents and digestible protein sources in our products to help your pet thrive while also reducing their ecological paw print. Check out our adult dog food, ideal for all breeds and made with no common allergens!

References

1. Association of American Feed Control Officals (AAFCO). Nutrient Requirements of Dogs and Cats. (2014). doi:10.1111/j.1748-5827.1963.tb01891.x

2. FEDIAF. Nutritional Guidelines. FEDIAF 323, 1178–1179 (2020).

3. Hang, I. et al. Impact of diets with a high content of greaves-meal protein or carbohydrates on faecal characteristics, volatile fatty acids and faecal calprotectin concentrations in healthy dogs. BMC Vet. Res. 9, (2013).

4. Herstad, K. M. V. et al. A diet change from dry food to beef induces reversible changes on the faecal microbiota in healthy, adult client-owned dogs. BMC Vet. Res. 13, 1–13 (2017).

5. Jackson, M. I. & Jewell, D. E. Balance of saccharolysis and proteolysis underpins improvements in stool quality induced by adding a fiber bundle containing bound polyphenols to either hydrolyzed meat or grain-rich foods. Gut Microbes 10, 298–320 (2019).

6. Grandi, M. et al. Effects of dietary supplementation with increasing doses of lactose on faecal bacterial populations and metabolites and apparent total tract digestibility in adult dogs. Ital. J. Anim. Sci. 17, 1021–1029 (2018).

7. Nery, J. et al. Influence of dietary protein content and source on colonic fermentative activity in dogs differing in body size and digestive tolerance. J. Anim. Sci. 90, 2570–2580 (2012).

8. Weiner, I. D., Mitch, W. E. & Sands, J. M. Urea and ammonia metabolism and the control of renal nitrogen excretion. Clin. J. Am. Soc. Nephrol. 10, 1444–1458 (2015).

9. Ephraim, E., Cochrane, C. Y. & Jewell, D. E. Varying protein levels influence metabolomics and the gut microbiome in healthy adult dogs. Toxins (Basel). 12, 1–16 (2020).

10. Sun, C. Y., Hsu, H. H. & Wu, M. S. P-Cresol sulfate and indoxyl sulfate induce similar cellular inflammatory gene expressions in cultured proximal renal tubular cells. Nephrol. Dial. Transplant. 28, 70–78 (2013).

11. Morrison, D. J. & Preston, T. Formation of short chain fatty acids by the gut microbiota and their impact on human metabolism. Gut Microbes 7, 189–200 (2016).

12. Aguirre, M. et al. Diet drives quick changes in the metabolic activity and composition of human gut microbiota in a validated in vitro gut model. Res. Microbiol. 167, 114–125 (2016).

13. Xu, J. et al. The response of canine faecal microbiota to increased dietary protein is influenced by body condition. BMC Vet. Res. 13, 1–11 (2017).

14. Templeman, J. R., Mansilla, W. D., Fortener, L. & Shoveller, A. K. Tryptophan requirements in small, medium, and large breed adult dogs using the indicator amino acid oxidation technique. J. Anim. Sci. 97, 3274–3285 (2019).

15. Sutherland, K. A. K., Mansilla, W. D., Fortener, L. & Shoveller, A. K. Lysine requirements in small, medium, and large breed adult dogs using the indicator amino acid oxidation technique1. Transl. Anim. Sci. 4, (2020).

16. Mansilla, W. D., Templeman, J. R., Fortener, L. & Shoveller, A. K. Minimum dietary methionine requirements in Miniature Dachshund, Beagle, and Labrador Retriever adult dogs using the indicator amino acid oxidation technique. J. Anim. Sci. 98, 1–10 (2020).