We always talk about how a fresh diet can help with your dog’s immunity, joint health, and other health benefits, but it’s so much more than that! A good diet can also shape their mood and behaviour.

If your dog is dealing with anxiety, restlessness, or other behavioural challenges, the root cause might not be a training issue. Instead, it could stem from their gut.

The gut and brain are deeply connected through what’s called the gut-brain axis, constantly communicating with each other. This means that the food your pet eats can influence their emotions, stress levels, and even how they respond to the world around them.

From their happy zoomies to moments of unease, in this blog, we explore how these behaviours and mood have a connection to their gut health.

What is the Gut-Brain Axis?

The gut-brain axis is a remarkable two-way street of communication between your dog’s gut and brain. It’s not just about digestion; this system impacts how your dog feels, reacts, and behaves.

At the core of the gut brain axis is the gut microbiota—a bustling ecosystem of bacteria, fungi, algae, and other microorganisms living in your dog’s intestines [1]. You might think of ‘fungi’ or ‘algae’ in a negative light but these tiny inhabitants play enormous roles in maintaining gut health and, surprisingly, mental well-being.

Here’s how the gut and the brain communicate:

Enteric Nervous System (ENS): The “Second Brain”

The ENS comprises millions of neurons lining the digestive tract, and it is a powerhouse of communication. These neurons send constant updates about the state of the gut to the brain via the vagus nerve—a major communication highway.

It is often called the “wandering nerve” because it stretches from the brainstem to the abdomen. This cranial nerve links the central nervous system to the enteric nervous system and governs digestion [2]. It’s how we know we’re full when food fills our gut.

In pets, the vagus nerve regulates key functions like smooth muscle contractions in the intestines and digestive secretions.

However, this system doesn’t just inform the brain about digestion but also sends signals that affect mood and has a role in helping to calm the heart rate after a stressful situation. This critical connection helps the gut communicate subtle changes to the brain, influencing both physical and emotional responses.

Sympathetic Nervous System: Fight, Flight, or Freeze

When your dog is stressed, their brain releases adrenaline and noradrenaline (or epinephrine and norepinephrine respectively). These hormones prepare them for action (or inaction) by triggering responses like rapid breathing, increased heart rate, and even a speed up or sudden stop in digestion [3]. For example, in an unfamiliar situation like a pet hotel or boarding home, your pet may experience diarrhoea or constipation due to this stress response.

Hypothalamic-Pituitary-Adrenal (HPA) Axis: Stress Manager

With the sympathetic nervous system, the brain communicates to the gut, however the reverse is also applicable. Research has shown that gut microbiota affects the development of the neural system in the HPA axis which governs how your dog’s body handles stress. With an unbalanced gut microbiome, cortisol—the stress hormone—is released, which shapes the stress response system [4].

While cortisol is necessary in maintaining bodily functions, excess cortisol in the body can impair the immune system and lead to other serious issues like diabetes and kidney damage.

Immune Signalling: A message board for gut microbiota

Another way the gut microbes interact would be with the immune cells in the gut lining, affecting how the immune system responds to health threats. This connection even extends to the brain via the production of cytokines—tiny proteins that help dictate inflammation. To put it in simpler terms, they allow your cat or dog’s body to withstand germs and viruses [5].

Gut Bacterial Metabolites: The Power of SCFAs

Healthy gut bacteria ferment dietary fibres to produce short-chain fatty acids (SCFAs), such as acetate, butyrate, and propionate. These SCFAs aren’t just good for gut health—they also influence brain function, crossing the blood-brain barrier to impact mood and behaviour [6].

This is all due to the work of the vagus nerve which perceives the SCFAs, through its afferent fibres, distributed in the intestinal wall.

Beyond these mechanisms, the gut microbiota contributes to producing critical hormones like dopamine and serotonin, which are vital for emotional balance and motivation [7].

How Does a Bad Gut Reflect on Your Pet’s Behaviour?

In healthy dogs, the gut microbiota is a harmonious mix dominated by beneficial bacteria such as “Bacteroidetes, Fusobacteria, and Firmicutes and, to a lesser extent, of the phyla Actinobacteria and Proteobacteria” [8]. However, factors like aging, stress, and illness, but most importantly, a poor diet can disrupt this balance. An imbalance in gut microbes leads to a condition called gut dysbiosis.

It is a condition where the intestinal barrier has a weakened integrity, affecting gut permeability. A strong barrier is important as a weakened one can result in pathogens and toxins easily infecting their bloodstream and causing an imbalance in their immune system. It also puts them in an inflammatory state with the production of proinflammatory cytokines [9].

This would be a sign of a leaky gut. In a healthy pet, they would have a strong intestinal barrier to keep foreign and unwanted materials like bacteria, food allergens and toxins out. Ingested food travels throughout the entire gastrointestinal (GI) system and nutrients are absorbed through the GI tract to enter the bloodstream for everyday functioning.

However, for a pet with a leaky gut, their body will be more susceptible to absorbing harmful substances along the way such as bacteria, antigens and undigested food particles. These substances pass through the intestinal lining and into the bloodstream, which increases their risk of developing several diseases like inflammatory bowel disease, chronic hepatitis or pancreatitis [10].

With an unbalanced microbiome, not only can it cause leaky gut, but the microbiota can also produce unwanted neurotransmitters such as cortisol from the HPA axis that can directly impact mental health. Cortisol further weakens the gut defences and changes nutrient absorption, absorbing specific bacteria and hindering beneficial ones [11]. This in turn disrupts bile acid synthesis and metabolism, creating an environment that favours harmful bacteria instead.

Research has also drawn links between gut bacteria and conditions like obesity, Alzheimer’s disease, and anxiety. Anxiety can reflect on their behaviour through problematic signs like increased fear, food aggression, resource guarding or difficulty adapting to new environments [12].

Hence, having a balanced gut microbiome is very important for overall health and mental well-being for your best friend.

A Healthier Gut, A Happier Dog

A balanced gut can work wonders for your dog’s mood, behaviour, and overall health. This is achievable through a complete and balanced less processed diet as gut bacteria produces metabolites such as SCFAs from undigested dietary fibres, crucial in maintaining the balance in the gut [13].

Sources of dietary fibres that are safe for both dogs and cats can include carrots, pumpkin and broccoli. SCFAs possess anti-inflammatory and strengthen your pets’ immune responses.

Another superpower of a healthy and balanced gut microbiota is its ability to produce dopamine, which is a ‘feel-good’ chemical. In hand with bacillus strains, it plays a significant role in the regulation of said chemical, essential for reward-driven behaviour and motivation [14]. Additionally, dopamine is the precursor to norepinephrine which modulates the behavioural response to stress and anxiety. This means that when the gut-brain axis is in harmony, your pet is more likely to be calm, adaptable, and resilient in stressful situations.

The Role of Prebiotics and Probiotics

Prebiotics and probiotics go hand in hand. Probiotics are live bacteria that add to the beneficial population in your dog’s gut. Research done on the Neurobiology of Stress showed that probiotics have been shown to improve stress response, memory, and even cognitive function [15].

Probiotics help regulate both the central and enteric nervous systems by calming the stress response through the HPA axis, by limiting the proinflammatory cytokine production, and supporting hormonal balance in the body.

If you’re looking for probiotic rich food for your pet, try water kefir, plain yogurt, sauerkraut or cottage cheese. They contain live organisms that can do wonders for your cat or dog’s gut.

On the other hand, prebiotics are the fuel that keeps probiotics thriving. These non-digestible fibres promote the growth of good bacteria in the colon, ensuring your dog’s gut microbiome remains diverse and balanced. Together, prebiotics and probiotics create the perfect environment for a healthy gut—and a happier dog.

The Grateful Pet’s Secret Weapon: Prebiotic Seaweed

At The Grateful Pet, we’ve taken the guesswork out of gut health. Our meals feature prebiotic seaweed, a natural powerhouse of nutrients and fibres that nurture your dog’s gut microbiota.

We use elkhorn sea moss, a type of seaweed naturally rich in iodine and vitamin K which helps in maintaining your dog’s cardiovascular and bone health. Harvested from the waters in Sabah, they are then fermented with active prebiotics to break down the raw seaweed into forms that are easily digestible making it an even more powerful prebiotic for your pet.

By incorporating prebiotic seaweed into our dog and cat food recipes, we ensure your pet gets the best of nature’s gut-friendly ingredients—all in one delicious meal. Our minimally processed fresh meals are available either gently cooked or raw meals and contain additional sources of prebiotics such as blueberries, carrots, spinach and pumpkin (applicable to our dog food).

Through understanding and supporting the gut-brain axis, you can profoundly impact your cat or dog’s emotional and physical health. Explore our range of meals and discover how The Grateful Pet can transform your dog’s health from the inside out!

Reference:

[1] Microbiome definition re-visited– Journal of Microbiome, June 2020 https://pmc.ncbi.nlm.nih.gov/articles/PMC7329523/
[2] Does My Dog Have a Gut-Brain Axis?– My Pet Nutritionist, March 2022 https://mypetnutritionist.com/post/does-my-dog-have-a-gut-brain-axis/
[3] Relieve Your Pet’s Stress-Related Diarrhea– Deb M. Eldredge https://www.fearfreehappyhomes.com/relieve-your-pets-stress-related-diarrhea/
[4] Gut-Brain Axis Impact on Canine Anxiety Disorders– Veterinary Medical International, January 2024 https://pmc.ncbi.nlm.nih.gov/articles/PMC10827376/
[5] Cytokines– Cleveland Clinic, March 2023 https://my.clevelandclinic.org/health/body/24585-cytokines
[6] The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication– Front. Endocrinol, January 2020 https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2020.00025/full
[7] Enzyme Promiscuity in Serotonin Biosynthesis, From Bacteria to Plants and Humans– Front Microbiol, April 2022 https://pmc.ncbi.nlm.nih.gov/articles/PMC9048412/
[8] Difference of gut microbiota composition based on the body condition scores in dogs– Journal of animal science technology, March 2020 https://pmc.ncbi.nlm.nih.gov/articles/PMC7142278/
[9] Intestinal permeability– BMC Gastroentology, November 2014 https://pmc.ncbi.nlm.nih.gov/articles/PMC4253991/
[10] Leaky Gut Syndrome– VCA Animal Hospitals https://vcahospitals.com/know-your-pet/leaky-gut-syndrome-in-dogs
[11] Altered Gut Microbiome Composition in Dogs with Hyperadrenocorticism– Robert W. Li, August 2024 https://www.mdpi.com/2076-2615/14/19/2883#
[12] Gut-brain axis in 2016– Nature Reviews Gastroenterology & Hepatology, January 2017 https://pubmed.ncbi.nlm.nih.gov/28053341/
[13] Short Chain Fatty Acids (SCFAs)-Mediated Gut Epithelial and Immune Regulation and Its Relevance for Inflammatory Bowel Diseases– Frontier in Immunology, March 2019 https://pmc.ncbi.nlm.nih.gov/articles/PMC6421268/
[14] Enzyme Promiscuity in Serotonin Biosynthesis, From Bacteria to Plants and Humans– Frontier in Microbiology, April 2022 https://pmc.ncbi.nlm.nih.gov/articles/PMC9048412/
[15] Probiotic consumption relieved human stress and anxiety symptoms possibly via modulating the neuroactive potential of the gut microbiota– Neurobiology of Stress, January 2021 https://pmc.ncbi.nlm.nih.gov/articles/PMC7816019/