Dr. Al Townshend

Guardians are aware that most dogs, and especially cats, do better when the bulk of their total daily nutrition comes from protein and fat, not carbohydrates. However, some question whether a high protein recipe affects a pet’s mood or behavior.

The internet frequently comments on this high protein discussion, specifically as it relates to aggression. Some claim high protein causes their pets to be aggressive, and lower protein -when fed-  causes less aggression.  Others comment that higher protein levels benefit their pet both physically and mentally.

While the science behind protein levels influencing mood and behavior is complicated, it’s important to understand the bigger picture.

In the pet’s body, mood and behavior are regulated by hormones and neurotransmitters.
Neurotransmitters are defined as, “a chemical messenger that carries, boosts, and balances signals between neurons, or nerve cells, and other cells in the body”.

When discussing neurotransmitters in relation to protein, we typically look at two protein amino acids – Tryptophan and Tyrosine.

Tryptophan is an essential amino acid that is necessary to produce serotonin (a neurotransmitter). It is found in moderate concentrations of most meats found inside pet foods. Increased levels of serotonin in the brain have been shown to contribute to feelings of well being and happiness in humans. Increased levels in pets should have the same effect, therefore, reducing any tendency toward aggression and support recovery from stress. This would suggest that since levels of tryptophan are not high in the protein sources commonly used in pet foods, the higher the level of protein, the greater the level of tryptophan.

However – this is where things gets complicated.

In order for the brain to produce serotonin, tryptophan must get into the brain. There is a protective barrier in the brain that protects the brain from certain substances. In order for tryptophan to pass that barrier, it must compete with other proteins for the transporter system that carries substances into the brain. The ratio of Tryptophan to other amino acids competing for the transport system must be high and that’s where the problem is thought to occur. The higher the total protein level in the diet, the lower the ratio and therefore, less tryptophan actually gets into the brain.

The best way to raise the ratio and get more tryptophan in the brain is to supplement.

Tyrosine, a non-essential amino acid, has also been shown to reduce stress and ease the mood in humans, is found in high concentrations in high protein recipes for pets.

While a high protein/low carbohydrate diet is an ideal way to feed, it may not have a significant effect on mood and behavior. That said, every pet is different and their response to a diet can vary.

Behavioral issues are some of the most common reasons Guardians are unhappy and frustrated with their pets. The right diet and supplements can make a difference, so be sure to discuss with any of the staff at your Pet Planet Store the next time you are there.

Additional Resources:

https://healthypets.mercola.com/sites/healthypets/archive/2017/11/20/hormonal-influences-dog-aggression.aspx
https://www.avma.org/News/Journals/Collections/Documents/javma_217_4_504.pdf
https://www.petmd.com/dog/centers/nutrition/evr_multi_how_your_dogs_food_affects_his_mood