Behavior & Protein: Does Protein in Dog Food Play a Role in Your Dog’s Behavior?

by Deborah E. Linder, DVM, MS, DACVIM (Nutrition)

We’ve previously talked about protein in commercial pet foods and home-cooked diets. Typically, our focus is meeting your pet’s biological needs. However, you may have heard friends, dog trainers, or even veterinarians talking about feeding a low protein diet to treat behavior issues. But what does a low-protein diet really mean, and how do these testimonials compare to the science?

What is a ‘Low Protein’ Diet?

Unfortunately using terms like low or high can be rather confusing in pet nutrition. Healthy adult dogs (over one year of age) need a minimum of 4.5 grams of protein for every 100 calories they consume (Unsure how this compares to the percentages on the back of a pet food label? You can convert the numbers by using the calculator here. Beyond this minimum requirement, there is no legal definition or even a general consensus of what exactly a ‘low’ or ‘high’ protein diet actually is. Each trainer, veterinarian, or nutritionist might have different ranges for what they consider in each category. In research or in recommendations, it’s important to clarify the actual amount of protein recommended and compare that to the minimum amount a pet needs and the current amount consumed by the pet.

What Protein Level is Safe to Feed to My Dog?

So long as diets are nutritionally complete and balanced for your pet (are above the minimum 4.5 grams protein per 100 calories and meet all the other nutrient requirements) and include an appropriate AAFCO statement, they are formulated to be balanced for healthy pets. There is also no maximum or safe upper limit for protein, but some pets may have limitations on the protein they can safely consume due to medical conditions. You should always consult your veterinarian about diet changes, especially if your pet is growing, pregnant, lactating, or has any medical conditions.

What Does the Research Have to Say About the Link Between Diet and Behavior?

Although certain amino acids from food have been found to alter the synthesis of neurotransmitters (chemical ‘signals’) in the brain, neurotransmitter release and behavior can also be influenced through training or changes in routine. A couple of studies have been done specifically on the relationship between protein and “problem” behaviors with conflicting results. For example, one study of a lower protein diet found that the behavior of dogs with owner-directed aggression (described as ‘dominance aggression in the study) and hyperactivity were unchanged, but that territorial aggression appeared reduced. Conversely, another study found that owner-directed aggression was the only behavior that seemed affected when dogs were fed a lower protein diet. There were some design problems with both studies – when the two diets that were tested were compared more carefully, the two diets tested were actually very similar in protein content and the two groups of dogs had similar overall protein intake, so it’s uncertain whether the changes seen were really due to variations in dietary protein versus other factors.

More research is needed to fully understand the potential behavioral impacts of various protein content in diets (and not just the total protein content but also the composition of the individual amino acids). Given the limited number of studies currently available, potential benefits of such diets are not strongly supported. However, as long as the diet chosen is good quality and is  complete and balanced for your pet, it may be appropriate to see if it improves your pet’s behavior (talk with your veterinarian first!). Overall, the best way to ensure healthy behavior for your dog is working with the right experts. Healthy dogs in need of training (e.g., pulling on leashes, jumping up on visitors to lick faces, etc.) should be seen by qualified force-free trainers. Dogs with abnormal behaviors (e.g., aggression, or normal behaviors that are displayed excessively or out of context) should be seen by a Board-Certified Veterinary Behaviorist. It’s also helpful to speak with your veterinarian as well, since many medical issues can look like behavioral issues so you’ll want to have your veterinarian examine your pet for pain or illness that may be making them act out of the ordinary.

For further reading, please see:

DeNapoli, J.S., Dodman, N.H., Shuster, L., Rand, W.M., Gross, K.L., 2000. Effect of dietary protein content and tryptophan supplementation on dominance aggression, territorial aggression, and hyperactivity in dogs. Journal of the American Veterinary Medical Association 217, 504–508.

Dodman, N.H., Reisner, I., Shuster, L., Rand, W., Luescher, U.A., Robinson, I., Houpt, K.A., 1996. Effect of dietary protein content on behavior in dogs. J. Am. Vet. Med. Assoc. 208, 376–379.

Deborah E. Linder, DVM, MS, DACVIM (Nutrition)

Dr. Deborah Linder, a board-certified veterinary nutritionist, is the head of the Tufts Obesity Clinic for Animals and has had articles appear in Eating Well, the Boston Globe, AARP, SHAPE, and XM Sirius Radio Doctor Channel. She has spoken at national and international conferences and a Capitol Hill briefing, and is an expert in pet obesity, nutrition communication, and in the human-animal bond. 

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