Dysbiosis and Behavioral Disorders in Dogs: The Role of the Gut-Brain Axis
- M.V. Claudia Barbieri
- Jun 18
- 4 min read
Approximately 80% of domestic dogs experience behavioral problems such as aggression, anxiety, or phobias. These issues affect the quality of life of both the dog and the guardian, leading to health concerns and disruptions in daily routines. Moreover, in some countries, behavioral disorders are among the leading causes of euthanasia and shelter abandonment, weakening the bond between humans and their canine companions.
While traditional approaches such as training and conventional medications like anxiolytics can help some dogs, they are often insufficient. Anxiolytics, in particular, may cause undesirable side effects, especially in chronic or complex cases. This has spurred growing interest in new therapeutic strategies, especially those targeting the gut-brain axis, such as nutraceuticals and homeopathy.
The gut-brain axis is a bidirectional communication network involving the nervous, endocrine, and immune systems, along with the gut microbiota. Often referred to as the "second brain," the gut influences mood, stress responses, and behavior through neurotransmitter production — with up to 90% of serotonin synthesized in the gut. Additionally, the vagus nerve provides a direct signaling pathway between the gut and the brain.
In this context, dysbiosis, defined as an imbalance in the gut microbiota, promotes neuroinflammation and can impair the production of short-chain fatty acids (SCFAs), such as butyrate, which are essential for both brain and gut health. Dysbiosis reduces the population of beneficial bacteria that produce SCFAs, resulting in lower levels of these vital metabolites and contributing to various health problems, including behavioral disorders.
Several key neurotransmitters that influence behavior are affected by the gut microbiota, including:
Serotonin, which is linked to anxiety and aggression when levels are low;
Dopamine, crucial for attention and motivation;
GABA, a neurotransmitter that calms the nervous system by inhibiting neuronal excitability, and which is produced by certain gut bacteria, especially Lactobacillus and Bifidobacterium.
Recent studies suggest that intestinal dysbiosis is associated not only with gastrointestinal and metabolic issues but also with behavioral changes. A review published in Animals (Kiełbik & Piłaszewicz, 2024) found that aggressive dogs tend to have lower serotonin levels and higher levels of inflammatory markers such as IL-6. The same review also reported that dogs fed a natural diet had higher fecal GABA levels and distinct microbiota profiles compared to those fed commercial kibble.
This evidence highlights a strong link between intestinal health and canine behavior and underscores the therapeutic potential of interventions such as:
Probiotics that modulate serotonin and GABA,
Fecal microbiota transplantation (FMT),
Prebiotics, and
High-fiber diets that promote SCFA production.
In addition to these, other supportive approaches, including nutraceuticals, medicinal mushrooms, and homeopathy, may contribute to improved gut health.
As discussed in previous articles, nutraceuticals are non-pharmaceutical supplements with therapeutic effects. In the context of dysbiosis, certain nutraceuticals such as Boswellia serrata, Eggshell membrane, and Palmitoylethanolamide (PEA) offer notable benefits, particularly in reducing inflammation and supporting mucosal integrity.
Boswellia serrata, extracted from the resin of its namesake tree, is rich in boswellic acids. These compounds inhibit 5-lipoxygenase (5-LOX), reducing leukotriene synthesis , which is a key pathway in both intestinal and systemic inflammation. Boswellia also supports mucosal healing and helps restore the gut barrier, often compromised in dysbiosis. Evidence suggests it may indirectly influence microbiota composition by reducing inflammation and promoting a healthier gut environment.
Eggshell membrane is another effective option for gut support. Rich in glycosaminoglycans, collagen, and other bioactive proteins, it exhibits anti-inflammatory properties and helps modulate immune responses, reducing intestinal mucosal inflammation. Components like hyaluronic acid and chondroitin sulfate further contribute to maintaining intestinal barrier integrity.
Palmitoylethanolamide (PEA) is a fatty acid amide naturally produced in the body and is well known for its anti-inflammatory and analgesic properties. In cases of dysbiosis, it stabilizes mast cells, which are often hyperactive in conditions like irritable bowel syndrome and dysbiosis and reduce the release of histamine and pro-inflammatory cytokines. PEA also supports the endocannabinoid system through activation of PPAR-α, influencing intestinal motility, permeability, and immune modulation. Additionally, it may reduce neuroinflammation and benefit the gut-brain connection.
While these nutraceuticals do not directly increase populations of beneficial bacteria, as probiotics do, they contribute to a more balanced gut environment. They help restore microbial balance, reinforce the gut epithelial barrier, and prevent the translocation of harmful bacteria and toxins. Furthermore, they promote immune homeostasis, reducing the excessive immune activation that can worsen dysbiosis.
Medicinal mushrooms are also effective allies in treating dysbiosis due to their prebiotic properties, immunomodulatory effects, and anti-inflammatory activity. Their polysaccharides, particularly beta-glucans, support intestinal health and microbial balance. Beta-glucans nourish beneficial gut bacteria such as Bifidobacterium and Lactobacillus, boosting SCFA production — especially butyrate — which plays a central role in maintaining the intestinal barrier and reducing inflammation. Medicinal mushrooms also regulate both innate and adaptive immunity, helping to restore immune balance often disrupted in dysbiosis. They support T-helper cell (Th1/Th2/Th17) regulation, strengthen gut-associated lymphoid tissue (GALT), and help repair the intestinal mucosa. Many species reduce the expression of pro-inflammatory cytokines such as TNF-α, IL-6, and IL-1β, which are commonly elevated in dysbiosis and gut inflammation.
Among medicinal mushrooms, the following are especially effective in addressing dysbiosis:
Reishi (Ganoderma lucidum): modulates gut microbiota composition, strengthens the intestinal barrier, and provides immune modulation, anti-inflammatory effects, and liver detoxification through its beta-glucans and triterpenes.
Lion’s Mane (Hericium erinaceus): promotes regeneration of enteric nerves and intestinal lining, while also reducing gut inflammation.
Turkey Tail (Trametes versicolor): rich in polysaccharide-K (PSK) and polysaccharopeptides (PSP), acts as a potent prebiotic and enhances immune system function by increasing natural killer cell activity.
Lastly, homeopathy can support the management of intestinal dysbiosis by activating the body’s intrinsic self-regulation mechanisms. This therapeutic approach stimulates the innate capacity for balance and healing through the use of ultra-diluted, individualized remedies. Homeopathy may modulate immune function, reduce chronic inflammation, promote mucosal barrier repair, and assist in restoring a healthy, balanced microbiota.
In conclusion, behavioral problems in dogs are not merely the result of inadequate management or training - they can also originate from physiological imbalances. In this light, combining strategies such as probiotics, FMT, nutraceuticals, medicinal mushrooms, and homeopathy offers a more holistic, natural, and effective approach to managing behavioral disorders in dogs, fostering a more harmonious relationship between humans and their canine companions.
#gutbrainaxis
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