By Dr. Becker
Most breeds of dogs have evolved to serve a certain specific purpose for humans.
Herding, retrieving and guarding are examples.
The purpose for which dogs were originally bred influences their physical and behavioral characteristics to this day, even though most dogs no longer have jobs to do for their humans.
Today's dogs also live inside houses with their families, where they are expected to behave with 'indoor manners.'
The natural instincts of dogs are often at odds with their modern day lifestyles.
As a result, millions of wonderful animals are dropped off at shelters each year by people who can't or aren't willing to manage disruptive canine behaviors like aggression, destructiveness, running away, excessive barking and house soiling.
Fortunately, there are also many people interested in learning how to deal more effectively with their pet's undesirable behavior.
Obedience training is the route many dog parents take.
Meanwhile, a handful of researchers are investigating the role nutrition plays in canine behavior, and whether adding or removing specific nutrients from the diet alters a dog's temperament and conduct.
How Certain Nutrients May Improve Problem Behavior in Dogs
Behavior in animals (including humans) is regulated by neurotransmitters and hormones. These substances have precursors, which are chemical compounds that precede them in metabolic pathways.
The main theory behind nutrition and its ability to alter canine behavior is that making these precursors more – or less – available, may make a difference in a dog's conduct.
Tryptophan, for example, is the precursor of serotonin (a neurotransmitter). It is believed its presence or absence may affect aggression and stress resistance in dogs.
Tyrosine, a precursor of catecholamines (hormones produced by the adrenal gland), may also affect aggression and stress resistance.
Let's take a look at some of the nutrients being studied for their possible beneficial effects on canine behavior.
Tryptophan and Tyrosine
Tryptophan is one of the large neutral amino acids (LNAA) that can cross the blood-brain barrier depending on how much free tryptophan and other LNAA are available in the body.
Increasing dietary tryptophan through supplementation can increase the amount of serotonin in the brain, which has been shown to reduce aggression and improve recovery from stress in some animals. Even though tryptophan is found in protein-containing foods, it is in relatively small supply compared to other LNAA. And in fact, a high protein meal actually decreases the ratio of tryptophan to other LNAA. This is why dietary supplementation is recommended.
Tyrosine, another amino acid, has also been shown to have a beneficial effect on stress in humans and other animals.
Unlike tryptophan, tyrosine is usually found in high concentrations in high protein meals.
A few studies conducted outside controlled experimental environments have been used to measure the impact of lower protein diets on aggressive dogs.
The results are largely inconclusive. In addition, while there may be a link between low dietary protein and decreased aggression in other types of animals, I'm unconvinced this is a useful approach for carnivores. Just as feeding your dog a raw diet will not, as some people believe, give him a taste for blood and drive him to randomly prey on cows or chickens or sheep, neither do I believe a diet rich in animal protein makes dogs more aggressive.
I would never recommend reducing the amount of high-quality protein in a dog's diet in an attempt to modify behavior.
Nourishing your pet with a grain-based diet will induce an insulin release (to balance high blood sugar after ingesting a high carb diet), and in turn, a cortisol release (to balance low blood sugar). Similar to people who have 10:00 am and 2:00 pm post-meal sluggishness (and require a nap), dogs will become more sedate after ingesting insulin-prompting carbohydrates.
Nourishing a dog with protein means no post-meal sluggishness … another way of saying, 'No nap required! Ready to play at any time!' Although carb-loading has become a common trend with humans, carb loading dogs (to induce the post-carb 'downer' effect) isn't an appropriate behavior moderation tool, in my opinion. Training and exercise are the correct tools to deal with behavior issues, not feeding an inappropriate diet to create a more sedate dog.
Physical exercise elevates serotonin levels in the body. Serotonin offsets cortisol and other stress hormones. Well-exercised dogs are much less likely to have behavioral problems than those who don't get enough opportunities for physical activity.
Most dog owners underestimate the amount of exercise their pet needs, and this is especially true for breeds with high activity levels. For healthy, young and middle-aged dogs, a minimum of 45 to 60 minutes of exercise twice a day is recommended. And at least 20 minutes of your pet's 45-60 minute sessions should involve heart-thumping aerobic exercise.
A recent stress-reduction study conducted with shelter dogs confirmed that even short (25 minute) sessions of exercise and human contact lowered the animals' cortisol levels and improved their scores on a behavior test.
Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid (PUFA) which in humans has a beneficial effect on inflammation and cognition.
Increased PUFA into the cellular membranes of the brain supports improved flow of neurotransmitters between cells.
Studies with rodents indicate DHA-rich diets improve learning ability and diets deficient in DHA have the opposite effect.
In a large-scale study of puppies fed an enhanced-DHA diet before and after birth, the pups made fewer errors during training and had a higher training performance index than puppies fed a diet containing normal amounts of DHA.
Since a diet rich in omega-3 essential fatty acids, including DHA, has so many other health benefits for pets, any positive impact they may have on a dog's behavior is icing on the cake.
Behaviors many dog owners find annoying are whining and begging for food, food stealing, trash and dumpster diving, and other similar conduct that seems to stem from feelings of hunger. Researchers have therefore considered the possibility that a fiber-rich diet, which is presumably more satiating to dogs, might play a role in curbing undesirable food-seeking behavior.
I absolutely disagree with this notion and would never encourage a dog owner to feed more dietary fiber as a way to correct food-seeking behavior.
Number one, I find it hard to imagine how more grains, carbs and starches could possibly be crammed into most of the popular commercial pet food brands on the market today. Most of those foods are already stuffed to the brim with fiber.
Number two, fiber is not species-appropriate nutrition for carnivores. Excessive amounts of fiber can block absorption of healthy nutrients into the small intestine. It acts as a mechanical barrier, preventing trace minerals, vitamins and antioxidants from getting to and through the walls of your pet's gastrointestinal tract.
Chances are, if a dog's food-seeking behavior isn't primarily learned (in other words, the behavior has been rewarded in the past), it's coming from a lack of adequate protein at the cellular level. Chronic deprivation of species-appropriate nutrients to the cells can result in feelings of constant hunger.
Behavior Modifying Nutrients Must Also Be Species-Appropriate
I absolutely believe the nutrition you feed your companion animal influences the workings not only of her body from the neck down, but also her brain and to some extent her behavior.
And I think it's wonderful that scientists are taking a look at cause-and-effect relationships between what dogs eat and how they behave.
But I think we need to be careful not to make this exploration all about the comfort and convenience of pet owners and others who share their lives with animals. Often what is most convenient for humans is not in the best interests of their pets. Our focus should be on discovering wonderful, natural, species-appropriate nutrients that promote the health and well-being of dogs while also helping to alleviate behavior problems.
In our efforts to curb certain undesirable dog behaviors through nutrition – especially if those behaviors are derived from natural canine instincts – we must insure we aren't creating ill health in the pets entrusted to our care.