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Pleun Broeren
19 april 2024 Reading time 4 minutes

Diarrhea in horses

You can recognize diarrhoea in horses by the thin manure, frequent fattening and the dirty tail and buttocks. The most important thing is to ensure that your horse does not become dehydrated! But what causes diarrhoea? And how can you prevent it?

Diarrhoea and manure water: what's the difference?

Diarrhoea and manure water are often mentioned in the same breath in horses. That's not surprising when you consider that some of the symptoms match. Yet there is a distinction between the two.

  • Manure water : During digestion, the fluid in your horse's intestines is bound and absorbed in the large intestine. But if, for whatever reason, your horse is unable to bind the moisture with the manure, manure water is created. This is pushed out through the stool and often runs down your horse's legs. Not a tasty sight!
  • Diarrhoea is often a greater burden on your horse's body and lasts longer than manure water. With diarrhoea, the entire intestinal flora is disrupted and your horse loses a lot of fluid and important electrolytes. In addition, the immune system is quickly affected in (severe) diarrhoea.

You have to be alert with both diarrhoea and manure water. Manure water can turn into diarrhoea if it lasts too long and the right treatment is not given. If the manure water does not decrease, or if your horse is becoming listless whilst passing diarrhoea, then it is wise to contact your vet. 

Causes of diarrhoea in horses

With diarrhoea, food passes through the gastrointestinal tract too quickly to properly absorb fluids and nutrients. This may be because the motility of the gastrointestinal tract is increased because the water-absorbing capacity of the intestine is reduced, or because there is an increased release of fluid and electrolytes in the intestine.

In the large intestine, digestion is not done so much by the body itself but by the bacteria that live there. They convert incoming fibres that the horse cannot digest itself into useful nutrients, such as volatile fatty acids. For a healthy functioning of the intestines, it is very important to keep these bacteria healthy, so that they can do their job well. All these bacteria together are called the intestinal flora. Too much spring grass, mouldy food, or sudden changes in the food, can disrupt the intestinal flora which can result in diarrhoea. Bad teeth, ingesting too much sand, certain infections, worms and stress are also causes of diarrhoea.

Stop diarrhoea in horses

Diarrhoea can dehydrate your horse and in some cases can be fatal. The most important thing with a horse with diarrhoea is to ensure that it does not become dehydrated. The administration of fluids, and also of nutrients, is then necessary. If you want to stop the diarrhoea in your horse, you must first find out what the cause of the diarrhoea is. This is best done in consultation with your vet, after which you can then draw up a treatment plan together.

Preventing horses with diarrhoea

Unfortunately, a horse with diarrhoea cannot always be prevented. Nevertheless, there are a number of preventative measures that you can take to reduce the risk of diarrhoea as much as possible:

  • When horses have not been on pasture all winter and return to pasture in the spring, this change can upset the bacteria in the gut. The young spring grass disrupts the intestinal flora which can lead to diarrhoea. Also, mouldy and spoiled food, or too sudden changes in a ration can disturb the intestinal flora. So always make sure that you build up grazing and ration changes slowly and avoid spoiled feed.
  • A horse with bad teeth cannot chew its food sufficiently. As a result, the food cannot be digested sufficiently, so that large pieces of food end up in the gastrointestinal tract. This can lead to diarrhoea. An annual visit to the dentist is therefore recommended!
  • Horses that walk a lot in a sand paddock, or in a poor pasture, can eat a lot of sand. When absorbing too much sand, the sand accumulates in the intestines, resulting in diarrhoea and/or colic. Regularly providing a sand-free course and giving enough hay on a sand paddock, or poor pasture, can help prevent diarrhoea.

Tip: make sure that horses get hay from a hard surface, this reduces sand absorption as the horses do not have to eat the hay directly from the sand. For example, put rubber plates under the hay. 

  • A good worm policy in the stable is very important to prevent diarrhoea. Manure testing four times a year and deworming once a year (usually in the autumn) with an extensive wormer reduces the risk of a worm infection, such as roundworms . Daily removal of horse manure from the pasture also lowers the infection pressure.
  • Horses that experience stress often express this in diarrhoea. To prevent diarrhoea, limiting stress factors is of great importance. Think of sufficient contact with congeners, sufficient grazing, not moving the stable too often, etc.  

Feeding tips for a good intestinal flora

Supplement for a stable intestinal function

The aim of the treatment for diarrhoea and/or manure water is to rebalance the bacterial population in the intestines. Pavo GutHealth has been developed especially for this. The 100% natural ingredients in this supplement – including barley grass, nettle, prebiotics and antioxidants – provide optimal support for healthy intestinal bacteria in the large and small intestine and thus help to prevent diarrhoea and manure water.

Pre- and probiotics 

To support the intestinal flora, both pre- and probiotics can be fed. Usually pre- and probiotics are mentioned in the same breath, but there is a big difference between the two. Prebiotics provide food for the hard-working bacteria in the large intestine. Probiotics are the bacteria or yeasts themselves.

Prebiotics mainly consist of fibres from roughage. The bacteria feed themselves on the fibres and produce volatile fatty acids, this process is called fermentation. The volatile fatty acids are then released into the bloodstream, allowing your horse to use it as an energy source. It is therefore very important to feed your horse sufficient quality roughage. Curious about the quality of your roughage? Do the Roughage Quickscan!

In addition to the most common roughage (grass, haylage and hay), there are various types of roughage alternatives . You can supplement, or even completely replace your roughage, with these alternatives if you have insufficient roughage, the quality is moderate or poor, but also if your horse can absorb little or no roughage (e.g. old horses), or your horse remains lean / lean. Pavo has four different roughage substitutes: Pavo FibrebeetPavo SpeediBeetPavo FibreNuggets and Pavo DailyPlus.

You can use probiotics when your horse's intestinal flora is disturbed. The balance between good and less desirable bacteria is gone, allowing the latter to expand. This can happen, for example, if your horse is given a course of antibiotics. When selecting a probiotic supplement or food, it is important that it contains live yeast. Dead yeast cells no longer have any effect.


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