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April 24, 2023

Can Too Much Protein in Dog Food Cause Diarrhea?

  • Nutrition
  • Protein
Dry kibble and a variety of fresh protein including turkey, salmon, eggs and peas

Let’s face it, when it comes to our dogs’ health, the consistency of their poop is something we all keep an eye on. That’s because stool quality can be a good indicator for how our dog’s digestion is doing, and a change could mean there’s something we need to address. It’s not uncommon for a change in your dog’s food to cause an upset tummy or diarrhea, but what about too much protein?

Can too much protein in dog food cause diarrhea?

There is research that suggests excess protein in dog food can be associated with reduced stool quality, including diarrhea (Volkman et al, 2017) (Zentek, J. 1995), but the full answer is more nuanced.
Theresa Lantz
Theresa LantzCompanion Animal Nutritionist

Whether this is the cause of your dog’s diarrhea depends on a number of factors.

Dietary protein in excess of what dog’s needs may lead to increased protein fermentation in the gut. This can create metabolites and may be harmful to the body. These metabolites can result in your dog having more frequent and smellier gas (Hughes et al, 2000), or lead to inflammation and kidney dysfunction (Ephraim et al, 2020). Research has also shown that too much protein in a dogs diet can reduce the pH in their gut, creating an environment where unfriendly bacteria can thrive (Zentek, J. 1995), which can upset the good bacteria, also known as the microbiome.

In recent years, it's been well documented that the population of gut bacteria differs between dogs fed high-protein diets versus a moderate-protein diet (Ephraim et al, 2020) (Pilla, R & Suchodolski, J. 2021). Interestingly, large breed dogs may be more susceptible to the potential side effects of high protein diets than smaller dogs, as they tend to have poorer stool quality in general (Weber et al, 2017).

In short, too much protein has been known to cause diarrhea and upset the gut bacteria and pH in dogs, but the long-term implications of high protein diets are still not fully known and require more research.

This might leave you wondering how much protein is enough for your dog, but it's important to point out that more does not always equal better. In fact, when a dog is fed a higher quality protein diet, less total protein is required. That’s because higher quality protein has an amino acid profile which matches what a pet needs, and is also highly digestible, making it a better source of the nutrient for the body to use (Elliot, D. 2006). High quality proteins include fresh meats, poultry and fish, along with the ‘perfect protein’, eggs. Although no optimal ranges for healthy dogs are established, AAFCO states that adult dogs need a minimum of 18% on a dry matter basis, however, we also know an individual pet’s protein requirement will vary throughout their life, based on multiple factors including breed and lifestyle.

Three bags of NOW FRESH dog food kibble

Our Recommendation

Now Fresh Dry Food Recipes for Dogs

Now Fresh recipes are crafted with moderate protein levels from high quality sources like fresh turkey, salmon & duck, and wholesome eggs. With each recipe perfectly balanced to your dog’s age & size, finding the perfect recipe has never been so simple!

Are there proteins to avoid?

Whether you should avoid certain proteins for your dog depends on whether your dog has any intolerances. In dogs, beef and chicken are the most commonly documented proteins associated with food intolerances (Mueller et al, 2016). Now Fresh dog food recipes are beef and chicken free, and a great option for pets who may have sensitivities to these more commonly used proteins. Additionally, Now Fresh offers a variety of poultry free recipes for dogs to enjoy, including recipes made from fresh trout, salmon and herring, as well as fresh lamb and pork.

How to introduce a new protein to your dog’s diet

When introducing a new food to your dog, whether a diet or a new treat, we always recommend a minimum 10-day transition in order to allow time for your dog’s system to adjust to the change. Some dogs can be extra sensitive and may even require longer. If at any time during this transition, you notice your dog is experiencing digestive upset, we recommend slowing down this transition.

Dog and kibble topped with pureed pumpkin

What is the cure for dog diarrhea?

Many at-home remedies exist for addressing diarrhea, from feeding a bland rice-and-protein diet to supplementing fibrous canned pure pumpkin, but there are many underlying reasons which can result in loose stools, and all may have different therapies. Plus, chronic diarrhea can contribute to dehydration and nutritional imbalances, so we always recommend consulting with your vet for their management recommendations and to help address the root cause.

The proof is in the pile

Your pup’s poop can say so much about their health, and a good stool can be an indicator of digestive and overall health. When dogs experience diarrhea or loose stools, diet may be a factor. High-protein diets can affect stool quality for a number of reasons, but ultimately a dog’s individual sensitivity and unique requirements are the greatest factors. Digestive health is key to overall health, and this can be supported by a balanced diet with fiber, good quality fats, and high-quality protein, like our Now Fresh recipes for dogs.

Not sure what’s right for your dog? Contact our animal health specialists at 866-864-6112 or for personalized advice.

Literature Cited:

1. Volkmann, M., Steiner, J.M., Fosgate, G.T., Zentek, J., Hartmann, s., & Kohn, B. 2017. Chronic diarrhea in dogs- retrospectives study in 136 cases. Journal of veterinary internal medicine.

2. Hughes., R, Magee., EA,& Bingham., S. 2000. Protein degradation in the large intestine: relevance to colorectal cancer. Current issues in Intestinal Microbiology. Vol 1(2).

3. Zentek, J. 1995. Influence of diet composition on the microbial activity in the gastro-intestinal tract of dogs. I. Effects of varying protein intake on the composition of the ileum chyme and the faeces. Animal physiology and animal nutrition. Vol 74 (1-5)

4. Ephraim, E., Cochrane, C., & Jewell, D. 2020. Varying protein levels influence metabolomics and the gut microbiome in healthy adult dogs. Toxins. Vol 12(8).

5. Pilla, R., & Suchodolski, J. 2021. The gut microbiome of dogs and cats, and the influence of diet. Veterinary clinics: small animal practice. Vol 51(3).

6. Weber, M.P., Biourge, V.C., & Mguyen, P.G. 2017. Digestive sensitivity varies according to size of dogs: a review. Animal physiology and animal nutrition. Vol 101 (1).

7. Elliot, D. 2006. Nutritional management of chronic renal disease in dogs and cats. Veterinary clinics: Small animal practice. Vol 36 (6).

8. Mueller, R.S., Olivry, T., & Prélaud, P. 2016. Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats. BMC veterinary research. Vol 12 (9).


Theresa Lantz

Theresa Lantz

Companion Animal Nutritionist

Theresa received both her BSc in Companion Animal Health and MSc in Animal Science from the University of Alberta.