The Gut & Behaviour

The Gut–Brain Axis in Dogs: What Do We Actually Know?

The gut and brain communicate through several biological pathways, including nerves, hormones, immune signalling and microbial metabolites. Research in dogs is growing, but the evidence is still developing and should be interpreted cautiously.

Introduction

The phrase “gut–brain axis” describes the two-way communication between the gastrointestinal system and the brain.

This communication involves several overlapping systems, including the nervous system, hormones, immune signalling and compounds produced within the gut.

The microbiome is part of that picture too.

Microorganisms can produce or influence metabolites that interact with the wider body, while stress and behaviour can also influence gastrointestinal function.

This makes the gut–brain axis scientifically interesting.

But it is also an area where claims can easily run ahead of the evidence.

In dogs, research is still developing, so it is important to separate what is biologically plausible from what has been firmly demonstrated.

Understanding the issue

What is happening?

The gut and brain communicate in both directions.

Signals from the brain can influence gastrointestinal movement, secretion and appetite.

At the same time, signals originating in the gut can influence the nervous, endocrine and immune systems.

One important route is the vagus nerve, which connects the brain with organs including the gastrointestinal tract.

Hormones and immune mediators provide additional communication pathways.

Microbial metabolites may also contribute.

Gut microorganisms produce a wide range of compounds as they use available substrates. Some of these compounds can interact with the intestinal environment and wider physiology.

This does not mean that individual behaviours can be reduced to “the microbiome”.

Behaviour is shaped by genetics, learning, environment, health, experience and many other factors.

The gut is one part of a much larger system.

Common factors

What can influence it?

Several factors can influence both the digestive system and behaviour.

Stress and arousal

Changes in routine, travel, kennelling, unfamiliar environments or stressful events can affect both behaviour and gastrointestinal function.

Diet

Food influences digestion and the substrates available to the microbiome.

Sleep and routine

Changes in sleep, exercise and daily routine can affect overall behaviour and wellbeing.

Pain or illness

Physical discomfort can alter behaviour and should always be considered if a dog's behaviour changes suddenly.

Medication

Some medicines can influence appetite, digestion, behaviour or the microbiome.

Individual temperament

Dogs differ greatly in how they respond to environmental and physiological changes.

For this reason, behaviour should always be considered in context rather than attributed to one biological system alone.

What you may notice

What can you observe?

Owners can often spot patterns that help provide useful context.

Changes in routine

Did a behavioural or digestive change begin around the same time as travel, visitors, kennelling or another disruption?

Appetite

Notice whether your dog is eating normally.

Stool consistency

Digestive changes may sometimes occur alongside changes in stress or routine.

Ability to settle

Consider whether your dog is resting and sleeping as usual.

General arousal

Notice whether your dog seems more restless, reactive or unsettled than normal.

Physical comfort

Reluctance to move, sensitivity to touch or sudden behavioural changes can sometimes reflect pain or illness and deserve veterinary attention.

Patterns are most useful when they are considered over time rather than based on one isolated event.

Everyday considerations

A consistent routine can be helpful for many dogs.

Regular feeding, exercise, rest and predictable daily patterns may reduce unnecessary disruption.

Diet should also be kept reasonably consistent unless there is a clear reason to change it.

If you are trying to understand a change in behaviour, avoid assuming that the gut is the cause.

Think about the wider picture:

recent changes in routine
environmental stressors
sleep
exercise
diet
physical comfort
age
training and learning history

If behaviour has changed suddenly or significantly, physical causes should be considered alongside behavioural ones.

When to speak to your vet

Speak to your vet if your dog shows a sudden or significant change in behaviour, especially if it is accompanied by digestive or physical changes.

Reasons to seek veterinary advice include:

sudden aggression or marked reactivity
obvious pain or sensitivity
repeated vomiting or persistent loose stools
loss of appetite
unexplained weight loss
marked lethargy
substantial changes in sleep or activity
confusion or unusual behaviour
persistent restlessness
a clear change from your dog's normal temperament

Behavioural changes can have medical as well as environmental causes.

Your vet can help rule out physical factors and, where appropriate, may suggest support from a qualified behaviour professional.

Where CaniNectar fits

CaniNectar is a complementary feed designed for use as part of the normal diet of healthy dogs.

It contains enzyme-rich malt extract — ERME — produced using a patented process designed to preserve naturally occurring digestive enzyme activity.

The nutritional rationale behind CaniNectar begins with digestion and the nutritional environment within the gut.

Because the gut and wider body are connected, research into digestion, microbial activity and metabolites is scientifically interesting.

However, CaniNectar should not be regarded as a treatment for anxiety, behavioural problems or other neurological or medical conditions.

If your dog's behaviour has changed significantly or you are concerned about their wellbeing, speak to your vet or an appropriately qualified behaviour professional.

References

Further reading:

Pilla R, Suchodolski JS. The Role of the Canine Gut Microbiome and Metabolome in Health and Gastrointestinal Disease. Frontiers in Veterinary Science. 2020;6:498.

Wernimont SM, Radosevich J, Jackson MI, et al. The Effects of Nutrition on the Gastrointestinal Microbiome of Cats and Dogs: Impact on Health and Disease. Frontiers in Microbiology. 2020;11:1266.

Cryan JF, O'Riordan KJ, Cowan CSM, et al. The Microbiota-Gut-Brain Axis. Physiological Reviews. 2019;99(4):1877–2013.

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