Modern nutrition science is showing us something remarkable: the gut is not just a digestive organ, it is an active part of the nervous system. Dr James Mosel, in Food Noise: Weight Loss Jabs and Smart Nutrition, describes the gut’s enteric nervous system (ENS) as a “second brain.” Containing as many neurons as a cat, the ENS communicates constantly with the brain via the gut–brain axis, using hormones, neurotransmitters and signalling molecules.

This communication works both ways. Just as the brain influences digestion, the gut can send powerful signals back, affecting behaviour, mood and wellbeing. For dogs, this means what goes into their bowl plays a direct role in how they feel and how they behave.

Ultra-Processed Foods: A Disruption to Gut–Brain Health

Ultra-processed dog foods typically rely on:

• Highly refined carbohydrates that cause rapid blood sugar spikes and crashes.
• Artificial colours, flavourings and preservatives which add chemical stress without nutritional benefit.
• Low-quality proteins and fillers that are harder to digest and leave little for the gut microbiome to thrive on.

These ingredients do more than reduce nutritional value. They can disturb the gut microbiome – the community of beneficial bacteria that interact closely with the ENS. An imbalanced microbiome may disrupt gut signalling, contributing to anxiety, hyperactivity, poor attention and even aggression in some dogs.

The Science of Gut–Brain Behaviour Links

Research in both humans and animals has demonstrated:

Microbial metabolites (such as short-chain fatty acids) produced from fibre fermentation can influence neurotransmitters like serotonin, often referred to as the “happiness chemical.”

• Chronic inflammation from poor diet can alter stress responses and emotional regulation.
• Balanced microbiota are associated with calmer, more adaptive behaviour in dogs, while dysbiosis (imbalance) correlates with digestive upsets and restlessness.

Put simply: a stable, well-fed microbiome sends calmer, clearer signals to the brain.

How McDug Nutrition Protects the Gut–Brain Axis

We formulate every recipe to respect the science of gut–brain health:

• High-quality proteins from trusted UK farms – easy to digest, rich in essential amino acids.
• Natural fruits, vegetables and botanicals – delivering prebiotic fibres to feed beneficial bacteria.
• Advanced Freshtrusion® technology – gently cooking ingredients at low temperatures to protect nutrients and avoid the degradation caused by heavy processing.
• Functional recipes in our Health & Wellness range – tailored for digestive care, skin and coat, and weight management, each designed to support microbiome stability.

By avoiding ultra-processed shortcuts, McDug supports a healthy gut microbiome, balanced neurotransmitter production and, ultimately, calmer, happier behaviour in dogs.

Key Takeaway

Good behaviour and good digestion are not separate issues – they are deeply connected through the gut–brain axis. Ultra-processed foods can interfere with this vital system, while nutritionally rich, minimally processed diets like McDug’s help your dug’s “second brain” thrive.

👉 Explore our Nourish Plus and Health & Wellness ranges to support your dug’s microbiome, behaviour and long-term wellbeing.

References

1. Mayer EA, Tillisch K, Gupta A. Gut/brain axis and the microbiota. J Clin Invest. 2015;125(3):926-938. doi:10.1172/JCI76304
2. Cryan JF, Dinan TG. Mind-altering microorganisms: the impact of the gut microbiota on brain and behaviour. Nat Rev Neurosci. 2012;13(10):701–712. doi:10.1038/nrn3346
3. Mondo E, Marliani G, Accorsi PA, Cocchi M, Di Leone A. Role of gut microbiota in dog and cat’s health and diseases. Open Vet J. 2019;9(3):253-258. doi:10.4314/ovj.v9i3.7
4. Guard BC, Suchodolski JS. Canine intestinal microbiology: digesting the gut microbiome. Anim Health Res Rev. 2016;17(2):163–177. doi:10.1017/S1466252316000204
5. Sandri M, Dal Monego S, Conte G, et al. Raw meat-based diet influences faecal microbiome and end products of fermentation in healthy dogs. BMC Vet Res. 2017;13(1):65. doi:10.1186/s12917-017-0981-z
6. Masuoka H, Shimada K, Kiyosue-Yasuda T, et al. Transition of the intestinal microbiota of dogs with age. Biosci Microbiota Food Health. 2017;36(2):27–31. doi:10.12938/bmfh.16-010