From Itching to Anxiety – It Starts in the Gut
Explore how your dog's gut microbiome influences everything from skin health to anxiety. Originally published in Hundesport magazine by NKK.
Introduction
Does your dog struggle with itching, loose stool, or seem more anxious than usual? While these issues might appear unrelated, they may share a common root cause – the gut. It may begin with something as ordinary as itching or loose stools. Perhaps the dog seems more lethargic than before, or more stressed and restless without any obvious reason. We change the food, check for parasites, and hope to find a simple explanation. But sometimes the cause runs deeper. For in the middle of the dog’s digestive system lies a living city of bacteria and microbes, working around the clock to keep the dog healthy.
The Forgotten Organ
The gut flora, or gut microbiome, is no longer a new concept. In recent years, it has appeared everywhere from advertisements to research articles. Yet few people truly understand how fundamental this invisible world actually is. Research suggests that it influences far more than digestion alone—among other things, the immune system, skin health, and behavior. In human medicine, we often refer to the gut as “the body’s forgotten organ.” The same applies to dogs. Research on the canine microbiome has exploded in recent years, and we now know that a healthy gut flora consists of a diverse community of bacteria working together, much like the inhabitants of a city. Some produce vitamins, others break down fiber or train the immune system to distinguish friend from foe. And, as in any society, chaos can arise. When beneficial bacteria are weakened or one group begins to dominate, we call this dysbiosis. It may sound dramatic that gut bacteria can make a dog stressed or itchy, but recent research shows that the gut communicates with the rest of the body. This happens through various so-called gut axes—communication pathways between the gut and the brain, and the gut and the skin. The g…
The Lifespan Perspective
The gut microbiota is built layer by layer throughout life, from puppyhood to adulthood. It actually contains more microorganisms than there are humans on Earth—an immense diversity that begins to take shape the moment a puppy is born. Puppies delivered vaginally acquire bacteria from their mother’s birth canal and skin, which form the foundation of their initial microbiome. In contrast, puppies born by caesarean section are primarily colonized by environmental and human-associated bacteria, resulting in a markedly different microbial starting point. After birth, the mother’s milk plays a crucial role. Colostrum and milk provide both antibodies and beneficial microbes that help establish the puppy’s intestinal immune system. When the puppy transitions to solid food, the gut microbiota changes rapidly and becomes more complex. Throughout life, the composition of the gut microbiota is shaped by diet, environment, medications, and stress. Several factors can reduce microbial diversity, while a varied diet helps support and maintain it (Sinkko et al., 2023).
Dysbiosis: When the Gut Falls Out of Balance
When the interaction between the gut’s microbial communities is disrupted, dysbiosis occurs—an imbalance in the composition, function, or localization of bacteria. This weakens the gut’s normal defense mechanisms and makes the body more vulnerable to inflammation and disease. Dysbiosis can have many causes, but antibiotics are among the most well known. Even a short course can dramatically reduce microbial diversity and allow pathogenic bacteria to proliferate. Several studies suggest that antibiotic treatment may disrupt the microbiome in ways that prevent it from returning to its original balance, potentially leading to long-lasting or permanent alterations (Chaitman et al., 2020; DeGruttola et al., 2016; Sinkko et al., 2023). Diet also plays a critical role. A monotonous diet provides limited access to fermentable fibers, resulting in reduced substrate for bacteria that produce short-chain fatty acids (SCFAs). These compounds are essential for maintaining strong intestinal cells, regulating inflammation, and preserving a healthy mucosal barrier. When SCFA production declines, both the mucosal lining and the integrity of the gut barrier are compromised, making the intestinal wal…
Dysbiosis and anxiety in dogs
It is easy to assume that anxiety and restlessness in dogs exist only in the mind. However, the gut and the brain communicate through what is known as the gut–brain axis, a finely tuned network of nerves, hormones, and signaling molecules. Several gut bacteria can actually produce or influence the levels of serotonin, dopamine, and gamma-aminobutyric acid (GABA)—the same substances that regulate calmness, security, and pleasure. As in humans, it is believed that most of a dog’s serotonin is produced in the gut. Recent research points to the role of the gut microbiota in understanding anxiety disorders in dogs. Studies show that the loss of beneficial bacteria and reduced microbial diversity in the gut can significantly affect canine behavior and contribute to the development or worsening of anxiety, stress, and restlessness. This aligns with findings from human research, where imbalances in the gut microbiota influence the production of neurotransmitters and, in turn, how the brain functions and responds to stress (Kiełbik & Witkowska-Piłaszewicz, 2024). A stable and diverse gut flora appears to be an important factor in the regulation of mental health in dogs. Interventions that…
Dysbiosis and itchy skin
In healthy dogs, the gut flora is in balance. It produces short-chain fatty acids (SCFAs) that have anti-inflammatory effects and help the immune system respond appropriately. However, when the gut becomes imbalanced, immune regulation also changes (Mahmud et al., 2022). The body may begin to overreact to harmless exposures such as pollen, dust, or proteins in food. That is when the itching begins. Research shows that gut dysbiosis can contribute to triggering or worsening skin conditions such as atopic dermatitis in dogs. Studies have found that dogs with atopic dermatitis often have a reduced presence of beneficial bacterial groups such as Prevotella and Lachnospiraceae. These microbes are important producers of SCFAs, particularly butyrate, which helps strengthen the gut barrier, regulate immune responses, and reduce inflammation (Sinkko et al., 2023). When levels of SCFA-producing bacteria decline, the production of anti-inflammatory metabolites that normally reinforce the gut barrier and keep immune reactions in check also decreases. This increases the risk of systemic inflammation, which can make the skin more reactive and susceptible to allergic responses (Moniaga et al., 2…
The Future of Canine Health
When we look at the bigger picture, it becomes clear that the gut microbiota plays a far greater role than many of us realize. Although it consists of microscopic organisms, it has an enormous impact on the health of our dogs. It influences the skin, the gut, mood—much of what makes our dog who they are. Within both human and veterinary medicine, we are now seeing how the microbiome can become an important tool for preventing, understanding, and treating disease. We know that more targeted, species-specific probiotics are on the way, and that better tools will emerge to determine when antibiotic treatment is truly necessary—and when it may do more harm than good. Research is being conducted broadly, far beyond the gastrointestinal tract, into the role of the microbiome in skin disorders, chronic kidney disease, cancer, and behavior-related problems. It is a rapidly evolving field, and we have only just begun to scratch the surface. Over the past year, I have worked with a large number of dogs struggling with everything from itching and allergies to stress and gastrointestinal issues. And a pattern is emerging: when we change the diet and introduce a targeted pre- and probiotic pro…
3 Things You Can Do for Your Dog's Gut Flora
1. Variety in the food bowl Just like us, the bacteria in the gut need a bit of inspiration! Rotate between different protein sources, offer fresh bones, and add berries and vegetables such as cooked carrots or broccoli. Variety gives more bacterial species something to feed on. The greater the diversity, the stronger the gut health. 2. Maintain an open dialogue about antibiotic use Sometimes antibiotics are necessary—and when they are, they should of course be used. However, it can be helpful to talk with your veterinarian about alternative treatment options and about how the gut microbiota can be supported before, during, and after treatment. 3. Let dogs be dogs! Dirt under the paws is a good thing! Contact with soil, other animals, and natural environments expands the microbial network and strengthens the immune system. When a dog gets to play, chew on bones, and sleep well, stress levels decrease. Lower stress levels are directly linked to better gut health.
Litterature
Sinkko, H., Lehtimäki, J., Lohi, H., Ruokolainen, L., & Hielm-Björkman, A. (2023). Distinct healthy and atopic canine gut microbiota is influenced by diet and antibiotics. Royal Society Open Science, 10(4), 221104. https://doi.org/10.1098/rsos.221104 DeGruttola, A. K., Low, D., Mizoguchi, A., & Mizoguchi, E. (2016). Current understanding of dysbiosis in disease in human and animal models. Inflammatory Bowel Diseases, 22(5), 1137–1150. https://doi.org/10.1097/MIB.0000000000000750 Chaitman, J., Ziese, A.-L., Pilla, R., Minamoto, Y., Blake, A. B., Guard, B. C., Isaiah, A., Lidbury, J. A., Steiner, J. M., Unterer, S., & Suchodolski, J. S. (2020). Fecal microbial and metabolic profiles in dogs with acute diarrhea receiving either fecal microbiota transplantation or oral metronidazole. Frontiers in Veterinary Science, 7, Article 192. https://doi.org/10.3389/fvets.2020.00192 Koh, A., De Vadder, F., Kovatcheva-Datchary, P., & Bäckhed, F. (2016). From dietary fiber to host physiology: Short-chain fatty acids as key bacterial metabolites. Cell, 165(6), 1332–1345. https://doi.org/10.1016/j.cell.2016.05.041 Pilla, R., & Suchodolski, J. S. (2020). The role of the canine gut…