Nutrition and Behavior

Nutrition and Behavior

Written by: Siven Zilber, clinical pet nutritionist

Can your dog's diet cause him to be aggressive or hyperactive?

How do you feel after eating a big bowl of pasta? For me, at first I get sluggish and tired, a short while after I start looking for something sweet to eat and then return being hungry again. 

We know that for humans, specific foods and nutrients can produce specific changes in the chemical balance of the brain which in turn affect both mood and performance. But are the same rules apply to our dogs? Let's grab our bowls and dig in.


Tryptophan is an amino acid found in protein foods like meat, chicken and fish, and is the precursor of serotonin, a brain chemical which is associated with feelings of relaxation, calmness and sleepiness. It also regulates sleep cycles and sensitivity to noise and touch. When you feed ingredients with tryptophan or foods that raise the blood levels of tryptophan, serotonin levels in the brain increase.

Although tryptophan is a constituent of protein, it is the consumption of carbohydrates that actually raises tryptophan levels in the blood and brain. This situation occurs because other amino acids found in protein overcome tryptophan and pass more effectively into the brain, which lower levels of tryptophan and thus serotonin.

Low levels of Serotonin (due to low levels of Tryptophan) are associated with increased aggression, especially defensive aggression, and decreased impulse control in dogs.  They can also exhibit signs of anxiety, fearfulness and all together be restless.

One study indicated that a diet with high protein concentration (32%) increased fear induced territorial aggression in dogs compared to low (17%) and medium (25%) protein concentrations. It didn’t however affect dominance aggression or hyperactivity. Another study reinforced this point and showed that low protein diet or a tryptophan supplement reduced dominance aggression, territorial aggression and hyperactivity in dogs

Simple carbohydrates

As stated before, feeding carbohydrates raises the level of serotonin which induces relaxation and calmness. This means that a diet with a high carbohydrate ratio may suit dogs who suffer from anxiety or aggression.

Also, for certain dogs, high-protein, low-carbohydrate diets may induce a serotonin deficiency which in turn could trigger carbohydrate cravings in order to correct the imbalance. These dogs may not only exhibit destructive behaviors around the house in their search for food but also sometimes signs of aggression.

On the other hand, because processed carbohydrates are transformed into simple sugars in the body, diets containing large quantities of simple carbohydrate (like many of the mainstream dog foods) cause an increase in blood sugar levels. These in turn can trigger behaviors such as anxiety, hyperactivity, low self control, irritability and fearfulness. 

I assume you are asking yourself "to feed or not to feed carbohydrates?" right? The solution is to feed diets containing balanced amounts of complex carbohydrates which will allow the availability of Tryptophan yet regulate the levels of sugar in the blood.

Energy surplus

Each dog has its dietary and energy needs according to his daily routine, activity level, health status, age and other personal considerations. Excess energy (Caloric) intake is stored in the body as fat and therefore constant intake of excess energy will lead in the long run to weight gain. Not only is obesity a major health and welfare issue for dogs, obese dogs also perform less vigorous activities such as running, jumping and playing. 

Energy restriction

Who of us isn’t familiar with feeling cranky when we are on a diet? So you won't be surprised when you hear that putting your dog on a diet and restricting his energy intake (lower quantities or foods with lower calories) can cause him significant frustration. This can be seen as different behaviors such as increased chewing, pawing, licking and holding objects in mouth.

When dogs are put on a diet, they are being fed below the recommended maintenance nutritional demands. This means the body receives less energy than it should in order to operate at a certain minimal level. The result is that the body starts to conserve energy and so the dog lowers its activity level.

In addition, studies showed that dogs given energy restricted diets started showing aggressive behaviors such as snaps, bites, focused barking and fighting. These behaviors decreased significantly as the time on the diet grew longer.

Dietary fiber

Adding dietary fibers to the daily diet of dogs on a weight loss program will provide them with feelings of fullness for longer periods of time after their meal. This in turn will decrease their hunger and search for food and decrease destructive and negative behaviors.

Specific deficiencies

There are some nutrients that the lack of them may result in certain behaviors:

Vitamin B1 (Thiamin) – compulsive behavior, coprophagia, neural issues.

Vitamin B3 (Niacin) – irritability, aggression, low reflexes.

Calcium – fearfulness, irritability, anxiety, disorientation.

Magnesium – aggression, muscle spasms, difficulty learning and memory problems.

Manganese – irritableness, allergies, deafness.

These deficiencies can only be known once conducting a blood test and so it's always better to talk to your vet if observing behavioral changes.

Common food additives

Many studies have linked the presence of certain chemical compounds in pet food to problematic behavior:

Artificial ingredients such as thickeners, binders, food colorings – lack of concentration, difficulty sitting still, fearfulness, and hyperactivity.

Preservatives such as BHA, BHT and Ethoxyquin – allergies, hyperactivity, neurotoxin – irrational fears, aggression, fearfulness and are highly linked to cancer.

The presence of pesticides and chemical fertilizers from grain ingredients – aggression, irritability and they are considered as cancer causing agents.

The liver is responsible for filtering the toxins our dogs consume. According to Chinese medicine, once it can no longer control the quantity of toxins it receives, our pets will demonstrate behavior of fear and aggression. 

Physical aspects

Many dogs suffer from allergies or sensitivities, either topical or digestive, which are connected to the food they eat. These health conditions have many symptoms and cause the dog to itch, scratch, lick himself, and have excessive thirst, feel abdominal pain or cramping, have nausea or loose stool and much more. These symptoms may also bring our dog to be restless, irritable and hyperactive.

In order to handle these behaviors, we first need to tackle the base problem which is the sensitivity. Usually this is done by a food change.

As we can see, the food our dog eats has much to do with his behavior and mood. Some diets many cause him to be restless, aggressive and hyper, while others will make him relaxed, content and easy to handle.

It's better if we know these dietary links in order to know if there is something which needs to be changed in order to help your dog and his behavior. Sometimes a simple change in diet may improve not only your dog’s quality of life, but yours as well.

A proper diet for your dog should be one with quality protein, fresh vegetables and balanced complex carbohydrates, without artificial preservatives and compounds and as close to his natural dietary needs as possible.   

Remember, quality nutrition can help you balance your dog’s behavior and contribute to their health.


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