Diets and Dietary Supplements for Anxiety in Dogs
Dietary treatments for anxiety in dogs can vary from diets to probiotics to supplements—here's how they work.
Over the past 100 years, our perception of the emotional needs of dogs has changed significantly. Many of our modern breeds were originally developed as working dogs. They worked alongside their human counterparts in the field, in the barn, or in the factory; and at the end of the day, dogs would eat what they could find. They often subsisted on scraps or leftovers; people thought little about feeding a balanced diet or truly addressing dogs’ nutritional needs, focusing simply on the caloric needs.
Thoughts about nutrition for dogs started to change in the 1860s, when James Spratt, an American entrepreneur, launched the first commercial food item specifically for dogs: the Meat Fibrine Dog Cake, a type of biscuit.1 Over the next 150 years, pet nutrition continued to evolve. Companies started producing diets to meet the nutritional needs of healthy dogs in various life stages: growth, maintenance, and old age. Next, dog foods were specially formulated to address nutritional needs for disease.
No longer is nutritional management limited to diabetes mellitus or renal insufficiency; it now also addresses emotional disorders such as anxiety. A variety of nutritional compounds and supplements that help improve emotional stability in companion animals have been identified. In addition, along with the nutritional component, movements such as Fear Free (fearfreepets.com) and Low Stress Handling (lowstresshandling.com) have brought the effects of stress on physical health to the forefront of veterinary care.
DETECTING STRESS IN DOGS
The veterinary nurse must be able to recognize patients’ behaviors associated with stress and anxiety as well as emotional wellbeing (TABLE 1). The easiest way to determine the various manifestations of stress is to consider what a happy dog looks like. Dogs experiencing little to no stress are mildly to moderately sociable with humans and other dogs. Their bodies are loose and relaxed. If the tail is wagging, it is at a moderate speed and held roughly at mid-level, in line with the spine.2 These dogs will approach novelty with curiosity, investigating it without startling or by moving quietly toward the stimulus. Comfortable dogs may or may not request physical affection by nudging a person’s hand with the nose, leaning into the person, or turning so their hind end is toward the person.
Amounts of stress can vary across a spectrum. Small amounts of stress are normal and good for the dog. A play session, for example, will induce a type of stress.3 However, behavior of an overly stressed dog would deviate from that of a contented dog.4 Most often, anxious dogs pant frequently; seem to have difficulty resting and relaxing, especially in novel situations; and even within their own home, anxious dogs may vocalize, avoid strangers, have difficulty resting, or display various levels of reactivity and aggression.4
Some dogs may display happy, contented behavior in most situations but stress behavior only in specific situations. Other dogs demonstrate some level of anxiety regardless of their environment.3 Diets and supplements can likewise be used situationally, or they can be used routinely to help manage the dog’s overall brain health and emotional wellbeing.
ROLE OF NUTRITION IN BRAIN HEALTH
Brain health begins long before anxiety can be manifested, even before birth. At the time of conception, the nutrition of the dam will affect the brain health of the fetus.4 After birth, structural development of the brain, cognition, and normal responses to the environment depend on access to proper levels of carbohydrates, proteins, and fats.
Carbohydrates are the primary energy source for the mammalian cell, but they also affect the function of the hypothalamic-pituitary-adrenal (HPA) axis. This axis is responsible for an animal’s successful and appropriate response to stressors.3 Too little of an HPA axis response and the animal cannot adapt appropriately; too great an HPA axis response and the animal’s response is exaggerated.
Proteins are organic molecules used primarily for structural development. The building blocks of proteins are amino acids. The animal’s genetic structure provides the programming needed for amino acids to be linked and formed into proteins, which are then used to build the structures of the body and brain.
Fats are critical for spinal cord myelinization. Myelinization is the developmental process by which each neuron is coated in a fatty structure, called myelin.3 It is this structure that enables the nervous system to effectively and quickly communicate with the rest of the body. In altricial (hatched or born in an undeveloped state and requiring care and feeding by the parents) species such as dogs and cats, myelinization occurs after birth, which is why altricial animals cannot walk until they reach the transition stage of development (around 2 to 3 weeks of age).4
NUTRITIONAL SUPPLEMENTS FOR BRAIN HEALTH
Essential Fatty Acids
Beyond the role of fat during development, essential fatty acids (EFAs) also help manage anxiety. EFAs are fats that cannot be produced by the body; they must be consumed. They comprise linoleic acid (an omega-6 fatty acid) and α-linoleic acid (an omega-3 fatty acid).5 EFAs have a variety of roles within the body, including mood, behavior, and inflammation. Because of their effects on brain health and other body systems, nutritional supplementation with EFAs is often used to assist dogs experiencing dementia or other signs of cognitive dysfunction.4
Certain proteinous compounds have been found to help reduce, manage, and to some degree treat anxiety in companion animals. l-Tryoptophan is an essential amino acid that is commonly associated with the consumption of turkey meat. l-Tryptophan plays a role in synthesis of serotonin.4
Serotonin is a neurotransmitter associated with mood stabilization, sleep cycles, and decision making.3 Serotonin is the neurotransmitter that is primarily targeted by psychotropics used to treat behavior disorders.4
Another product, 5-hydroxytryptophan (5-HTP), is the intermediate metabolite produced during the body’s synthesis of serotonin from l-tryptophan.3 It has been used to regulate sleep, depression, anxiety, aggression, and even pain.3 Studies in canids have been limited, and some have indicated the potential for 5-HTP toxicity when overdosed. One retrospective study, conducted by the American Society for the Prevention of Cruelty to Animals Animal Poison Control Center, identified 21 cases of accidental ingestion of 5-HTP by dogs, of which 19 dogs were symptomatic and 3 died.6
A safer alternative to 5-HTP is l-theanine. This amino acid can be used to help stabilize mood and has far less risk for toxicity or adverse reactions than 5-HTP.6 l-Theanine is most frequently found in the plant used to make green tea (Camellia sinensis), which has long been consumed for its calming properties. Studies have shown that l-theanine binds the receptors of glutamate, which is the brain’s primary excitatory transmitter.7 By occupying those receptors, l-theanine can help prevent overexcitement and, therefore, anxiety.7
Another noteworthy peptide is α-casozepine, which is a bioactive peptide originating from a S1 casein, a protein in cow’s milk. Various studies have shown that this product effectively decreases anxiety in cats,8 but its anti-anxiety effects in dogs are comparable to those of the pharmaceutical selegiline.9 α–casozepine is structurally similar to γ-aminobutyric acid, an amino acid that functions as an inhibitory (calming) neurotransmitter in the brain.
Beyond standard nutrients, veterinary medicine has begun focusing on the effects of probiotics on anxiety. “Stress colitis” is the term used for acute diarrhea associated with stressful situations in animals, such as boarding or travel. During an acute stress response, the body produces corticotropin-releasing factor, which mediates the HPA axis.3 Corticotropin-releasing factor binds to receptors in the gastrointestinal (GI) tract, leading to diarrhea. Chronic stress and activation of the HPA axis can increase the permeability of the GI tract, making the animal more susceptible to disease and other inflammatory processes.10 The brain and GI tract are very closely linked. Armed with this knowledge, researchers have explored ways to reduce the effects of stress by supporting the GI tract. One of the most common supportive products is the probiotic.
A probiotic is a type of supplement that contains strains of bacteria that are considered beneficial to GI health.10 For years, Enterococcus faecium has been the ingredient of probiotics for dogs, but a new species has recently come under scrutiny: Bifidobacterium longum (BL999). In a study conducted in 2008, consumption of these bacteria was shown to reduce GI symptoms associated with stress in humans;11 a newer study has shown that dogs experience similar relief.12 The veterinary community has since picked up on this research and started marketing new types of probiotics for dogs and cats, primarily to reduce the effects of anxiety.
So far, this article has explored individual compounds. Although it is possible to supplement with each sole ingredient, many companies have created accessible and easy-to-administer products that may include not just one but several active ingredients (TABLE 2).
Cognitive, behavioral, and emotional pathologies of companion animals are garnering attention in the research and clinical realms. Therapies for anxiety can vary from appropriate diets to probiotics to supplements. Every animal is different; fortunately, multiple options are available to help each patient achieve the best quality of life possible.
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12. McGowan RTS. “Oiling the brain” or “cultivating the gut”: impact of diet on anxious behavior in dogs. Proceedings of the Nestlé Purina Companion Animal Nutrition Summit, March 31-April 2, 2016;91-97.