Many pet parents are on the hunt for high protein diets, but what is the real reason behind this desire? Many people believe that dogs are obligate carnivores, like their friends, the cat, but in reality dogs have evolved greatly from wolves and are considered facultative carnivores, which means they can get their nutrients from both meat and plants. Facultative carnivores and omnivores eat both plants and meat (animal-derived food); they eat everything! Dogs can thrive on a diet that is not super high in protein or even in meat. 

So how much protein do dogs need? There are specific minimum protein requirements for dogs to be able to live their daily lives healthy and happy. These requirements come from the AAFCO and FEDIAF (18% DM and 22.5% DM for puppies). There are no optimal amino acid or protein concentrations recommended by these officials for dogs and only one maximum concentration for the amino acid lysine recommended (by FEDIAF). 

Although the official nutrient recommendations haven’t been updated, there has been published research that has looked into nutrient recommendations for different sized animals, weight control strategies, effects on the microbiome, senior diets, etc. These studies explain the possible impact of higher protein diets in different dogs. Other studies have investigated the importance of amino acid and protein digestibility or quality of the proteins used in the pet food industry to discover how much of the protein is actually accessible for the body to use. 

Quality over Quantity

Many pet parents look at pet food labels to check how much protein is included in the pet food, but quantity isn’t everything. The quality of the protein included in the formula is important and many researchers have investigated the digestibility of protein and amino acids of several different ingredients used in pet food. The digestibility is important when considering protein sources as this is the amount of the nutrient able to be absorbed and used by the body.

Below is a table with a few pet food ingredients and their essential amino acid digestibilities. Highly digestible amino acids would have values over 80%. These digestibilities can then be used to calculate digestible indispensable amino acid scores-like values. These scores use reference protein patterns from AAFCO-recommended values to determine protein quality for dogs at maintenance or for growing puppies. 

Pet food ingredients and their amino acid digestibility (%). 

Microbiome

When looking at the canine microbiome, several studies have investigated the effects of high protein diets. The microbiome is the collection of microbes (like bacteria, fungi, viruses) that naturally live inside our bodies and our dogs. The microbiome is influenced by genetics, the environment, medication use and of course diet! Diets high in protein led to increases in fecal pH, branched chain fatty acids and indole sulfates in dogs. Higher fecal pH can be a sign of low beneficial bacteria due to low short chain fatty acids (SCFAs) and fibre in the diet. Branched chain fatty acids are associated with protein fermentation while SCFAs are associated with carbohydrate fermentation. An increase in protein fermentation can lead to cell damage in the intestines, while carbohydrate fermentation and the production of SCFAs can lower pH, have anti-inflammatory properties and provide energy to the cells in the colon. 

Kidney Disease

Higher protein diets can lead to a shift in gut bacteria to favour protein breakdown and a higher fecal pH, which are both associated with higher levels of metabolites linked to inflammation and kidney disease. 

Weight Management

A higher protein (and fibre) diet is often used to manage weight loss in dogs. A high protein, high fibre diet leads to increased fullness whilst maintaining muscle mass in dogs trying to achieve weight loss. 

Different Breeds/Sizes/Activity Levels

Dogs come in all different shapes and sizes, so you would assume that not all of their nutritional requirements are exactly the same. Some studies have investigated different amino acid requirements in small, medium and large breed dogs and found they differ for each size. Protein requirements may also be higher for high performance dogs or dogs with an illness. 

It is important to remember that any excess protein we feed our dogs is not stored in their bodies. The nitrogen in the excess protein is converted to urea and excreted in their urine, making your lawn yellow whilst contributing to harmful ammonia in the environment.

Check out more detailed information and references in our previous blog. 

Main takeaways:

• There are no optimal protein or amino acid recommendations for dogs, but there are required minimum amounts of protein and essential amino acids

• High protein diets may have detrimental effects on the canine microbiome and kidneys

• High protein and fibre diets can keep dogs healthy during weight loss 

• Different breeds/sizes of dogs may have different protein/amino acid requirements

• Excess protein is not stored in the body

• Protein quality over protein quantity

References

1. Do, S. et al. Amino acid digestibility and digestible indispensable amino acid score-like values of black soldier fly larvae fed different forms and concentrations of calcium using the precision-fed cecectomized rooster assay. J. Anim. Sci. 99, 1–10 (2021).
2. Reilly, L. M. et al. Use of precision-fed cecectomized rooster assay and digestible indispensable amino acid scores to characterize plant- And yeast-concentrated proteins for inclusion in canine and feline diets. Transl. Anim. Sci. 4, (2020).
3. Matin, N., Utterback, P. & Parsons, C. M. True metabolizable energy and amino acid digestibility in black soldier fly larvae meals, cricket meal, and mealworms using a precision-fed rooster assay. Poult. Sci. 100, 101146 (2021).
4. Oba, P. M., Utterback, P. L., Parsons, C. M., De Godoy, M. R. C. & Swanson, K. S. Chemical composition, true nutrient digestibility, and true metabolizable energy of chicken-based ingredients differing by processing method using the precision-fed cecectomized rooster assay. J. Anim. Sci. 97, 998–1009 (2019).
5. Deng, P., Utterback, P. L., Parsons, C. M., Hancock, L. & Swanson, K. S. Chemical composition, true nutrient digestibility, and true metabolizable energy of novel pet food protein sources using the precision-fed cecectomized rooster assay. J. Anim. Sci. 94, 3335–3342 (2016).