It is traditionally known that a healthy digestive tract is fundamental to optimal health in man and beast, and science is now helping us to understand why. The digestive tract is not just involved in the extraction of nutrients from food, but also in immune and cognitive function. The horse has a highly specialised digestive system that has evolved over millions of years. He has adapted to thrive on a low energy, fibrous diet.

Key points of the horse’s digestive system:

  • Small stomach producing acid continuously

  • Fast small intestine transit rate

  • Limited amylase activity in the small intestine (amylase digests starch)

  • Huge, voluminous hindgut full of fibre-fermenting microbes

  • Well adapted to processing a high throughput of low quality, fibrous material

When it goes wrong

Gut disturbance in the horse can be caused by a number of diet related factors including a shortage of dietary fibre, a diet too rich in grain and starch or too much starch fed in a single meal, a rapid change of diet (especially the forage component), stress and intensive exercise and certain drugs. We also know that the risk of colic is increased with very little and extremely high levels of exercise and this is likely to be due to the effects that this has on the digestive system.

  • Resulting conditions of poor diet and management strategies for the horse include:

  • Oral stereotypies like crib-biting (used to be called vices)

  • Certain types of colic

  • Tying up during exercise

  • Some types of over-reactivity and anxiety under saddle

  • Gastric ulcers

  • Acidic gut syndrome and hindgut dysfunction

  • Obesity, equine metabolic syndrome and insulin dysregulation

  • Laminitis

How to keep the gut healthy

Although it is important to treat each horse as an individual, there are some guidelines that we can follow to help promote a healthy digestive system:

  • Feed ad lib forage or limit any period of fasting to no more than 4 hours

  • Ensure correct hydration, with fresh water available all the time

  • Feed enough fibre

  • Limit starch intake to a maximum of 1 g per kg bodyweight per meal (max of 3 meals)

  • Make all dietary changes gradually and this includes forages (and grazing) as well as hard feed

  • Minimise stress, with good training and management routines

  • Support the gut with appropriate supplements if necessary

Supplement support

Supplements can be very useful for digestive system support. The important groups include probiotics, prebiotics and calmatives.

Gastri-Kalm is a specially formulated stomach-supporting supplement, which should be given to all horses and ponies that are prone to or at risk of stomach problems. At-risk lifestyles for gastric (stomach) ulceration would include those:

  • in intensive competition schedules

  • in regular fast work

  • who have limited social contact

  • who have limited access to grazing

  • on restricted forage

  • who fast regularly

  • who are on high starch diets

  • who are on non-steroidal anti-inflammatory drugs


Digestive system health is fundamental to whole-horse health and we should take great care of our horses’ digestive tracts. Feeding with the digestive tract in mind and using supportive supplements strategically will help to ensure our horses stay optimally healthy in mind and body.

Tags Gut Health