What does good digestive health mean for the horse?

feeding to reduce colic

Whether your horse is at peak competition age, a foal, or a veteran, the state of its digestive health will significantly affect its general health and well-being.

Claire Gotto, an equine veterinary advisor, explains the importance of good digestion in keeping horses happy and healthy.

Clair Gotto Equine Veterinary advisor and a grey horse
Claire Gotto, equine veterinary advisor

 How Important is Fibre in a Horse’s Diet?

Horses are designed to eat a diet high in fibre rather than the high-concentrate feeds we often give them. Fibre is a source of energy that horses have evolved to eat for a large portion of their day. The digestion of fibre takes place in the hindgut by bacteria; the process is called fermentation, and it is important for a horse’s daily function.

The product of fermentation is volatile fatty acids, which provide the horse with slow-release energy. Volatile fatty acids absorbed from the hindgut account for 60 to 70% of a horse’s energy requirement. Two-thirds of the digestive tract is developed to digest fibre and if a horse doesn’t get enough in their diet, it can affect the balance of microflora in the digestive tract.


Also, a diet too low in fibre and too high in carbohydrates can lead to secondary problems such as laminitis, gastric ulceration, colic and tying-up.

Horses grazing (MSD owned)
Horses grazing. Image copyright MSD

What Causes Poor Digestion in Horses?

Drastic changes to a horse’s diet can cause an imbalance of microbes in the hindgut. Other contributing factors to hindgut disturbance include extreme exercise, transportation, stress and antibiotic therapy, all of which can negatively affect the fermentation process.

Fermentation requires a stable population of healthy microflora, but the hindgut is a sensitive ecosystem. Anything that alters the established gut flora destabilises the ecosystem causing an imbalance which results in a shift in volatile fatty acid production. This can cause a fall in hindgut pH, known as hindgut acidosis, which causes inflammation in the area.

What Indicates Poor Digestion in Horses?

Horses may display subtle signs of hindgut disturbance or dysbiosis, which can go unnoticed. Signs include:

  • negative behavioural changes: grumpy when girthed up and when the rider’s legs are applied, rearing and bucking
  • a general sense of your horse not being quite right
  • serious clinical signs include weight loss, diarrhoea or colic

How do I Maintain my Horse’s Digestive Health?

There are many ways to help horses maintain good digestion and hindgut health, such as:

  • feed a balanced diet with plenty of fibre
  • give concentrate feed in small quantities
  • include a hindgut supplement in their diet
  • allow as much access to grazing pasture as possible, or provide ad-lib hay (depending on the individual horse’s needs)
  • ensure any dietary changes are made gradually
  • avoid stressful situations, if possible

Digestive Health in Foals

Image copyright MSD.
Image copyright MSD.

Foals are born with very few bacteria in their guts, so when they suckle their first milk, known as colostrum, bacteria in the milk quickly start to colonise the gut and the microflora.

However, the foal’s environment is full of bacteria, no matter how clean it appears. If healthy microflora are not established quickly, harmful bacteria from the environment can start to colonise the gut.

These bacteria can cause serious problems, such as severe diarrhoea and sepsis. So, it’s best to encourage healthy bacteria to colonise the gut as quickly as possible.

Supplementing with prebiotics and postbiotics is important at weaning. As a foal’s nutrition changes from milk to hard feed and grass, so it can be quite a stressful time, which can cause an imbalance in hindgut microflora.

Digestive health in competition horses

Competition horses can experience heightened lifestyle factors that can increase the likelihood of hindgut imbalance. For example, racehorses are unlikely to be turned out to pasture often and tend to be fed high-carbohydrate, low-fiber diets.

Poor digestive health can lead to poor performance and behavioural issues in competition horses. Strenuous activity, travelling, staying away at shows, and management changes around competition times, can all contribute to stress in horses and adversely affect digestion.

Speak to your vet if you have concerns about your horse’s general health and well-being, as signs of poor digestion aren’t always tangible.

Digestive health in older horses

Older horses can be at risk of hindgut imbalance and disturbance due to a number of factors that come with age.

Senior horses are often on long-term pain relief, for example, non-steroidal anti-inflammatory painkillers for osteoarthritis or lameness, which can have a detrimental effect on hindgut microflora.

Cushing’s disease is quite common in horses over 15 years old. Diagnosed horses are more likely to have reduced immunity, leading to an increased risk of bacterial infections. Vets often prescribe antibiotics, which can adversely affect gut microflora.

Related posts