Pet food nutrition: it’s not just about high protein

No published scientific data has shown the benefits of high protein in dog food, nor that it’s the root cause of any health issues. Protein quality is key.

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The color of the lawn may indicate whether a dog is getting excess protein in its diet, and the quality of that protein. l Andrea Gantz
The color of the lawn may indicate whether a dog is getting excess protein in its diet, and the quality of that protein. l Andrea Gantz

As discussed in my previous blog post (“Your dog is not a wolf! Pet food companies, take note”), the retail trend for pet foods has leaned toward meat-rich and high-protein products. Crude protein in dry dog foods can range from 15.5 percent (Hill's Prescription Diet k/d) to greater than 60 percent (WysongEpigen) depending on dogs’ nutritional needs. In the case of renal disease, Jacob et al. (2002) demonstrated that lowering crude protein in dogs improved the mortality rate in dogs (i.e., dogs lived longer). Nevertheless, no published scientific data has demonstrated that high protein is the root cause of any health issues. Nor has published scientific data demonstrated the benefits of high protein.

But how much protein is too much protein? 

Well, it depends. Do you want yellow or burned-out spots in your lawn, random lush green spots in your lawn or a nice consistent lawn? Although this question may appear to be random in nature and mocking, it does address and help answer the question of how much protein is too much. Additionally, this will likely answer some of your consumer complaints you may receive daily (burnt lawns or high fecal volume).

Let me explain.

In healthy dogs, high protein is not going to be a health problem since any excess protein will be used for energy and the by-products excreted via urine or feces. When talking about protein quality in diets, there are numerous things to consider. Factors include the concentration and composition of essential amino acids, non-amino acid nitrogen (nucleic acids, amines, amides), digestibility and bioavailability (Giesecke et al., 1982; NRC, 2006; Yamka et al., 2007; Gross et al., 2010). Factors impacting digestibility and bioavailability include but are not limited to: ash content, fiber content, ingredient interactions, processing time, processing temperature and anti-nutritional factors (Gross et al., 2010). Therefore, it is important to realize that none of these items are considered when crude protein is listed on the bag.

High crude protein does not equal high quality

If the protein is poorly digestible, then the excess protein is excreted into feces (fertilizer = lush green spots in your lawn) or fermented into some nasty fecal and flatulence odor compounds like cadaverine and putrescine (Gross et al., 2010). If you have dogs that sleep in your room at night, you have likely fallen victim to this crime.

If the protein is highly digestible (absorbed and bioavailable), it will be used for structural protein synthesis (such as muscle tissue), synthesis of enzymes and hormones (plus other nitrogen-containing compounds) and, finally, deaminated for energy utilization and storage (i.e., fat or glycogen). The excess nitrogen resulting from the deamination is excreted as urea in the urine (Gross et al., 2010; NRC, 2006). High concentrations of urea in the urine will result in your lawn having yellow and burnt spots. Didn’t think I would come back to the color of your grass, did you?

Pet food protein data

Given the popularity of the internet and the ability for people to easily publish their opinions, I once again encourage pet food manufacturers to provide the appropriate information to pet parents. I have seen blogs where the solution to high-protein, high-quality diets is to teach their dog how to go only in one section of the yard. (Really?) Now that’s some sound nutritional advice!

If we, as nutritionists and manufacturers, want to follow the consumer trends, then we need to provide proper information to pet parents and the people advising them (i.e., veterinarians). For instance, providing basic information like protein digestibility and protein-to-calorie ratios can ensure that animals consume the proper amount of protein per day (i.e., grams of intake), and this simple information can help combat obesity (to be discussed at a later date). Additionally, excess protein adds unnecessary costs to foods, which ultimately gets passed onto the pet parent.

Not decimal point nutrition

So, what is the right answer? I can tell you the answer does not rely on nutritional guarantees nor decimal point nutrition (15.5, 25, 30 nor 60 percent crude protein) but rather on actual daily protein intake (grams per day). This is dependent on stage of life, individual metabolism, daily activity and disease state. Providing better feeding guides on websites can help pet parents and vets alike dial in on an individual pet’s needs given each unique situation. Lastly, we need to let the professionals handle lawn maintenance, not the dogs!

Next topic: grain-free vs. grains

Next time we will discuss this topic: “Grain-free isn’t better than grains.” If there are topics you would like to have discussed, feel free to comment below or reach out via LinkedIn:



Blaxter, K. L. 1989. Energy Metabolism in Animals and Man. Cambridge Univ. Press, New York, NY.

Giesecke et al., 1982. Purine availability and metabolism in dogs fed single-cell protein or RNA. J. Nutr. 112:1822.–1826.

Gross et al., 2010. Macronutrients: In Small Animal Clinical Nutrition, 5th Edition. Topeka, Kansas: Mark Morris Institute, p. 49-105.

Jacob F, et al. 2002. Clinical evaluation of dietary modification for treatment of spontaneous chronic renal failure in dogs.J Am Vet Med Assoc. 220(10):1495.

NRC. 2006. Proteins and Amino Acids. in Nutrient Requirements of Dogs and Cats. Natl. Acad. Press, Washington, DC. p. 6–138.

Yamka et al., 2007. The impact of dietary protein source on observed and predicted metabolizable energy of dry extruded dog foods. J. Anim. Sci. 85:204–212

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