Bite for Bite: Examining the Link Between Nutrition & Your Pet’s Behavior

Molly Grim, B.A.

We’ve all felt it: The late-afternoon energy crash between lunch and a second cup of coffee, or the on-edge irritability that preceeds that hours-overdue dinner.  As humans, we know that food is a vital tool in stabilizing our mood and energy levels, and for maintaining overall health.  Providing all the necessary brain and body fuel for ourselves and our families helps ensure more relaxed, cooperative relationships between comfortably satiated individuals. If we don’t function optimally on imbalanced nutrition, could what’s in Fido and Fi-fi’s bowl be contributing to their bothersome behavior? This is a multi-faceted question that is being increasingly investigated by veterinarians, pet trainers and animal behaviorists alike.

The arena of pet nutrition is one of great controversy, ranging from those who swear by the most expensive of packaged commercial brands and veterinary formulas, to proponents of raw, natural, home-cooked or even vegan recipes.  Unbiased and scientifically significant studies are relatively few, and no one diet has been found unequivocally superior.  It is universally important, however that all changes in your pets’ food be made slowly, and with the approval of your veterinarian.  That said, there is an arsenal of information surrounding domestic animal nutrition and feeding habits that can be utilized by pet parents who wish to become informed consumers (or cooks!).

As meat-eaters, one of the dietary cornerstones for dogs and cats is protein.  Incomplete and complete proteins can be obtained through primary meat sources or balanced combinations of meat, vegetables and grains.  Balance is the key term, as evidence increasingly supports the role of protein in the effects of serotonin in both dogs and cats.  Serotonin is a chemical that serves to regulate an animal’s mood, sleep-wake cycles, level of arousal, and sensitivity to pain/stimuli.  Before serotonin can be produced, there must be adequate levels of its precursor, Tryptophan (think turkey-induced post-thanksgiving coma) which comes from meat sources.  Many pet foods include corn and other simple carbohydrates as a primary protein, though these lack tryptophan.  This eventual deficit of serotonin may manifest as hyperactivity, aggression, hypersensitivity or restless sleep.  Unfortunately, feeding primarily large quantities of meat may create a similar fate.  Some studies have found that other amino acids present in animal products may provide competition for tryptophan, which is again unable to reach the brain in the form of feel-good serotonin.

Though the majority of owners and animal professionals would agree that dogs and cats benefit nutritionally and behaviorally from eating meat, those included in commercial foods may be comprised of controversial by-products and/or chemicals.  Preservatives and dyes in human food have been linked to allergies and behavioral difficulties, and there is increasing evidenced to support this relationship in animals.  In order to avoid some commercial pet foods’ more gruesome components, look for the following on the label:
The first 3 ingredients are those present in the highest amounts. Favor unambiguous statements such as “lamb meat” or “chicken” rather than “meat product/byproduct” that could potentially include euthanized, diseased or road-killed animals. Preservatives such as vitamin C and E (tocopherols) may be safer than artificial preservatives in question regarding cases of hyperactivity, cancer and self-injurious behavior.

Another important player in providing a balanced diet are carbohydrates.  Within this category are wheat, various grains and vegetables.  Wheat and other grain allergies are becoming increasingly common in pets and may contribute to gastric sensitivity, scratching, self injurious behavior or irritability of skin or mood.  It is crucial that any allergies be ruled out by your veterinarian if your pet is exhibiting any of these symptoms.  Barring allergies, carbohydrates may still be problematic.  House training/soiling difficulties in dogs have been attributed to an excess of carbohydrates by some veterinarians and trainers.  The looser stool that results from the high carb, larger volume diets are harder for the dog to retain, and harder for the owner to clean up, resulting in an accident-prone dog and a frustrated owner (who may have a harder time responding properly to the accident—see the blog on house-training.)  Additionally, carbohydrates provide an energy surge for a couple of hours following mealtime, creating the potential for hyperactivity/mood irritability cycles of behavior.  We may see this in our pets as destruction, rough play or overzealous biting in puppies.  In commercial pet foods, potentially beneficial “whole grains” in the ingredients do not exclude those that have been stripped or rejected for human consumption.  It might be best to select a pet food that explicitly labels the grain such as “brown rice.”

In some cases, the form of the pet’s food may contribute to behavior, particularly when chewing and house-training are in question.  Canned foods contain high moisture contents that may be excessive for a dog trying that is learning to refrain from urinating in the house.  Similarly, a total lack of crunchy kibble has been blamed for increased chewing habits when a dog has no outlet to appropriately use his jaws.  In catering to cats, their drive to hunt and stalk its dinner in small, frequent meals, might be better fulfilled by splitting fluffy’s daily ration into small portions hidden about the house.  This uses mental and physical resources (that aren’t being spent on the sofa’s arm) while providing the proper ration at satiety-maintaining intervals.

Cats aren’t the only pets that benefit from frequent feedings, and the method of mealtime delivery may be one of the most important considerations regarding nutrition and behavior.  While free feeding (particularly high-carb foods) may lead to hyperactivity and obesity, once-a-day feedings for both dogs and cats can contribute to aggression, stress, anxiousness and irritability in response to a drop in blood glucose.  To avoid this, a properly-sized ration can be divided into smaller portions fed twice or three times daily.  If possible, caching, hiding, or enclosing your pet’s food in a food-dispending treat is a great way to keep them mentally and physically occupied while satisfying some of their animal feeding instincts.

It has been suggested that some adverse aggressive and food-refusal behaviors can be correlated with a pet’s feeding environment and poor digestion.  While the ingredients in a pet’s food are certainly important in digestion, stress and nervousness can also contribute to gastric upset.  In addition to messy stools and under- absorbed nutrients, poor digestion can contribute to irritability, biting, whining, restlessness and other signs of ill-ease.  Though it is important to work with a trainer and behaviorist to avoid aversive food-guarding or aggression problems, a nervous dog or cat might benefit from being allowed to eat in a location they perceive to be safe and quiet.  You or your trainer/behaviorist can observe your pet to determine if there is a proper room or kennel that will allow unrushed, relaxed eating and digestion. To help encourage satiety feelings and quality sleeping patterns, feeding your pet within an hour or two of “bed time” might be helpful.

Finally, to address those upturned whiskers of the picky-eaters, the refusal of a healthy, nutritionally balanced food may be linked to our human desire to love and please our pets.  Just as we can use food as a reward to capture and train positive behaviors, food-refusal responses can be reinforced by the eventual addition of a novel food or tantalizing treat.  Though pet owners mean well, that coercive nugget of liver or spoonful of tuna after the beloved fluff-ball balks at his bowl, conditions a “if I sit and wait rather than digging in, that human will give me something great!” response.  Presto: Human is trained!

The links between pet nutrition and behavior are still in need of further study.  Until then, the few completed experiments and a wealth of anecdotal evidence helps fuel healthy discussions about how to best provide for out pets.  As long as essential vitamins, minerals and other nutrients are provided to your pet, safe and slow experimentation with different diets may be a beneficial piece of the behavior-modification puzzle.