Brain & Cognitive Disorders
Stress-Related Behavioral Disorders
Pets may become stressed from exposure to loud noises, separation from the owner (i.e., owner leaving pet alone), new people or pets in the household, or changes in routine. Chronic stress can affect behavior, as well as gastrointestinal and immune health, and (in cats) lower urinary tract health. Approximately 70% of dogs demonstrate stress-related behaviors including shaking, excessive barking, destructive behavior, pacing, repeated lip licking, and yawning. Stress-related behaviors in cats include house soiling, aggression, and overgrooming.
The gut-brain axis refers to the bidirectional communication occurring between the intestinal tract and the brain. Research has shown that the gut microbiome influences development of the nervous system, brain biochemistry (e.g., neurotransmitter production), response to stressors, and behavior. Certain probiotics, in turn, can modify the gut microbiome, reduce stress, and influence behavior. Additional supplements, such as fish and milk-derived ingredients, may also influence behavior; their mechanisms of action are still being explored.
Key Messages
- A placebo-controlled, crossover Purina study showed that the probiotic strain Bifidobacterium longum CNCM I-5642 NCC3001 (BL999) reduced a number of stress-related behaviors in dogs.
- Another controlled, crossover Purina study showed that feeding dogs a diet with increased levels of fish oil significantly reduced day-to-day stress-related behaviors. When fed this diet, dogs were also less reactive and in a more positive state in response to stress-provoking stimuli.
- Supplementing anxious dogs with milk-derived alpha-casozepine or caseinate hydrolysate, fish hydrolysate, or L-theanine or other plant extracts may help reduce some stress-related behaviors. However, modifying dietary protein levels and/or levels of the amino acid L-tryptophan to reduce anxiety in dogs is not consistently supported by research.
- In cats, nutritional management of stress behaviors has not been explored as extensively.
- Early Purina research has shown the proprietary strain of Bifidobacterium longum reduced stress and associated behavior, e.g., pacing, in cats.
- Other research suggests that alpha-casozepine and L-tryptophan may help reduce anxiety in cats.
Related Tools and Content:
Feline Lower Urinary Tract Health: The Role of Diet
Nutrition plays a role in the maintenance of feline lower urinary tract health.
Volume 12: Systemic Effects of the Gut Microbiome
Learn how the gut microbiome shapes behavior, affects skin health, and influences feline chronic kidney disease—plus explore innovative strategies to modulate the microbiome for better outcomes.
The Intersection of Diet and Behavior: A Panel Discussion
Learn about the microbiota–gut–brain axis, how nutrition can support behavioral and cognitive health in dogs and cats, and the importance of feeding management in addressing behavioral feeding issues.
To Share With Pet Owner:
Tips to Comfort Cats and Dogs with Separation Anxiety
You can help ease your pet’s separation anxiety.
How to Cope with Puppy Separation Anxiety
Here are several tips to help ease your puppy’s anxiety when left alone.
How to Help Dogs Afraid of Thunderstorms
You can help ease your dog’s fear of thunderstorms.
Tips for Easing Your Dog's Fear of Fireworks
If your dog is afraid of fireworks, you can help ease the fear.
Tips for a Pet-Friendly Relocation
If you are planning a relocation to a new home, follow the tips to help your pet throughout the process.
Additional Resources
McGowan, R. T. S. (2016, March 31–April 2). "Oiling the brain" or "Cultivating the gut": Impact of diet on anxious behavior in dogs. Proceedings of the Purina Companion Animal Nutrition Summit: Beyond essential. Fort Lauderdale, FL, United States, 87–93.
Beata, C., Beaumont-Graff, E., Diaz, C., Marion, M., Massal, N., Marlois, N., Muller, G., & Lefranc, C. (2007). Effects of alpha-casozepine (Zylkene) versus selegiline hydrochloride (Selgian, Anipryl) on anxiety disorders in dogs. Journal of Veterinary Behavior, 2, 175–183.
Davis, H., & McGowan, R. T. S. (2021). Effect of Bifidobacterium longum 999 supplementation on stress associated findings in cats with FHV-1 infection. Journal of Veterinary Internal Medicine, 35(4), 116, NM01.