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Can Gut Health Affect Behaviour in Horses?

When we think about horse behaviour, factors such as training, management and temperament often come to mind first. However, growing research suggests there may be another important piece of the puzzle: gut health.

The connection between the digestive system and the nervous system is known as the gut-brain axis. The gut microbiome constantly communicates with the brain in horses. This can influence not only digestion and nutrient absorption, but also stress responses, immunity and behaviour.

What is the gut-brain axis?

The gut-brain axis refers to the two-way communication system between the digestive system and the brain.

Several key systems are involved:

  • Central Nervous System (CNS): the brain and spinal cord
  • Enteric Nervous System (ENS): a network of neurons within the digestive tract that regulates gut function
  • Gastrointestinal Tract (GIT): the entire digestive system from mouth to rectum

While the connection between digestion, immunity and behaviour has been recognised for many years, scientific understanding of the gut microbiome's role within this relationship continues to evolve.

Importantly, communication works in both directions. Changes in the brain can influence the gut environment, while imbalances in gut microbes, known as dysbiosis, may affect neurological responses and behaviour.

How does the gut communicate with the brain?

The mechanisms involved in gut-brain communication are complex and are still being explored. However, several pathways are known to play a role, including:

  • Neural pathways
  • Endocrine signalling
  • Immune responses
  • Microbial metabolites

Together, these systems create a continuous flow of information between the digestive tract and the nervous system.

A key part of this communication network is the enteric nervous system, often referred to as the horse's "second brain". This extensive network of nerve cells sits within the digestive tract and helps regulate gut movement, secretions and blood flow.

Another important pathway is the vagus nerve, which connects the brain directly to the digestive organs. As part of the autonomic nervous system, it operates automatically, transmitting signals between the gut and brain without conscious control.

Neurotransmitters, the chemical messengers used throughout the nervous system, are active in both the brain and digestive tract. Research suggests that many of these signalling pathways may be influenced by the gut microbiome.

The stability of the gut microbiota can also influence digestive efficiency and nutrient absorption. These factors may affect hormonal signalling and metabolic processes that ultimately contribute to stress responses and behaviour.

Researchers are also investigating how prebiotics, probiotics and postbiotic metabolites may help support the gut microbiota and gut wall, and what role they may play within the gut-brain axis.

What does the research show?

The link between digestion and emotions is not a new concept, but modern research is providing greater insight into how gut health and behaviour may be connected in horses.

Much of this work focuses on the hindgut, where large microbial populations ferment fibre and contribute to normal digestive function.

Diet and behavioural reactivity

Diet has a significant influence on the composition of the equine microbiome.

Research has shown that high-starch concentrate diets can alter hindgut microbial populations and are associated with increased behavioural reactivity in horses. Studies examining dietary changes have investigated both shifts in microbial populations and behavioural responses during stress-based tests, including novelty exposure and startle challenges.

When horses were moved from a high-fibre forage-based diet to a low-fibre, high-concentrate diet, researchers observed:

  • Alterations in hindgut microbial populations
  • Changes in gut chemistry
  • Increased behavioural reactivity during novelty tests

These findings highlight the close relationship between dietary management, gut physiology and behavioural responses, supporting the concept of a gut-brain connection in horses.

How can you support the gut-brain axis?

As our understanding of equine gut health develops, maintaining a stable microbiome is increasingly recognised as an important part of supporting overall wellbeing.

One of the most effective ways to support the gut microbiome is through consistent management and feeding practices. Horses thrive on routine and sudden changes to diet, turnout or management can disrupt the balance of microbes within the hindgut.

Practical ways to help support your horse's gut health include:

  • Feeding a high-fibre, forage-based diet
  • Introducing feed changes gradually, particularly during seasonal transitions
  • Limiting high-starch concentrate feeds where possible
  • Maximising turnout and grazing opportunities when conditions allow
  • Maintaining a consistent daily routine
  • Providing targeted nutritional support for digestive health

Seasonal changes and gut health

Seasonal changes can be a particularly important time to focus on gut health. Changes in grass availability, forage quality, stabling routines and exercise levels can all influence digestive balance. Taking a proactive approach to feeding and management during these periods may help support both digestive function and overall wellbeing.

While research continues, growing evidence highlights the importance of maintaining a healthy digestive system and stable microbiome as part of supporting overall wellbeing and behaviour.

For riders and owners, this reinforces the importance of looking at the horse as a whole. Supporting gut health is not simply about digestion; it forms part of a wider approach to overall health, wellbeing and day-to-day management.

Looking for more support?

For more information on equine nutrition, digestive health and seasonal management, visit the NAF website, where you'll find educational resources and details on how to contact the NAF team for free nutritional advice.

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References 

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