Dealing with a horse that has diarrhea requires careful attention to their feeding plan and to their daily management.

In some cases, diarrhea is a temporary annoyance that resolves itself with minimal intervention. Chronic cases in which diarrhea persists for at least 7 to 14 days can require greater intervention.

A number of different contributing factors can lead to diarrhea in horses, including: [1][2]

  • Bacterial, viral, or parasitic infection
  • Inflammation
  • Drug administration
  • Stress
  • Toxins
  • Diet and feed changes
  • Dysbiosis
  • Malignancy
  • Heart failure
  • Liver disease

In general, anything that disrupts the microbial population within the horse’s gut or irritates the intestinal lining can negatively affect gastrointestinal health and digestive function, potentially leading to diarrhea.

Diet is the first thing to be critically assessed when a horse is suffering from diarrhea. [4] Horses prone to gut issues can benefit from a feeding program that maintains a stable population of microbes in the gut.

In this article, we discuss the top ten tips for feeding horses that experience diarrhea, including avoiding abrupt changes to the diet and reducing excess starch consumption.

What Causes Diarrhea in Horses?

The reason that your horse has diarrhea may be difficult to identify. There are a number of potential causes, including bacterial or viral infection as well as non-infectious causes.

Some of the most common non-infectious causes of diarrhea in horses include: [1][2]

It is important to remember that diarrhea is a symptom and not a disease. Horses often develop diarrhea due to other underlying conditions.

Unfortunately, the underlying reason can be difficult to determine and goes unsolved in 50% of cases. [5][6]

Diet and Your Horse’s Gut Health

Horses have a very sensitive digestive system which is easily disrupted by changes in their feed or routine.

Horses are hindgut fermenters, which makes them unique from most mammals. The hindgut plays a critical role in extracting energy from otherwise indigestible fibres found in forages. [7]

The cecum and colon which make up the hindgut are populated by a large community of microbes that ferment fibre in their diet. Normal gut function, digestion and immune health are highly dependent on the microbial population residing in the horse’s gut.

A major by-product of microbial fermentation is volatile fatty acids (VFAs), which are short-chain fatty acids that are absorbed and used as energy by the horse.

These VFAs are also integral to support the turnover of cells of the intestinal lining. The VFAs support the growth of new cells in the gut, reduce inflammation and keep a proper pH balance. [4]

Any disturbance or shift in the population of bacteria within the gut can impact VFA production which can result in diarrhea. [4] This is because the presence of VFAs greatly increases the absorption of fluid and sodium from the colon. [37]

Feeding your horse in a way that supports proper hindgut fermentation and a balanced microbial population can help to reduce the risk of diarrhea in horses that are prone to gut issues.

Feed changes can also help to resolve diarrhea in your horse if they are currently dealing with this problem.

If you are looking for help with your horse’s diet, submit your current feeding plan online and our equine nutritionists can review it and give you suggestions to support digestive function in your horse.

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Feeding Horses with Diarrhea

Horses that regularly experience diarrhea are at greater risk of becoming dehydrated or losing weight.

Diarrhea in foals often occurs with changes in gut motility and rapid transit of food through the digestive system. When feed and nutrients pass through the intestines too quickly, this reduces the amount of time for water and nutrients to be absorbed.

The result is loose, watery stools and reduced feed efficiency. Your foal is not absorbing as much water, nutrients and energy from the feed they consume, which can result in weight loss and other health problems. In adult horses, the additional load of poorly digested food is handled by the microbes without diarrhea resulting.

Some additional complications of chronic equine diarrhea can include:

  • Electrolyte (sodium) imbalance
  • Poor growth
  • Lethargy or poor performance
  • Poor skin, coat or hoof quality
  • Protein loss (hypoproteinemia)
  • Toxemia and Endotoxemia (absorption of toxins)
  • Laminitis (in severe cases)
  • Blood clotting abnormalities (rare, primarily with liver disease)
  • Sudden death with fulminant (ulcerative) colitis

As the cause of diarrhea is often unknown, it can be difficult to feed and manage horses that develop frequent bouts of diarrhea. If your horse has chronic diarrhea, their feeding program should be adjusted to minimize potential complications.

The first step is to have your veterinarian examine your horse to rule out infectious or other serious medical causes of diarrhea. Pathogenic organisms can be difficult to culture and a minimum of three cultures is typically recommended. Rectal examination, test for sand in the feces, abdominal radiographs, abdominal ultrasound, rectal biopsy and sampling of abdominal fluid may all be recommended.

If your horse is generally healthy but continues to experience diarrhea, feeding and management are your best options for resolving this symptom.

Below are some dietary recommendations to help minimize the onset of diarrhea and support the resolution of symptoms.

1) Ensure Adequate Nutrient Intake

Horses prone to diarrhea may be suffering from an undiagnosed gastrointestinal disorder, such as Inflammatory Bowel Disease. IBD often also involves the small intestine which is the site of simple carbohydrate, protein and fat absorption as well as most minerals and vitamins.

Chronic diarrhea with both small intestinal and hindgut involvement is often associated with malabsoption of nutrients and weight loss. These horses may require additional nutrients or caloric energy in order to meet core nutritional needs, support immune function and repair their intestinal lining.

Horses that experience long or frequent bouts of diarrhea may have reduced food intake or low appetite. An extended period of reduced food intake could result in nutrient deficiencies and impair the overall health and well-being of the horse. [5]

In particular, horses with impaired hindgut function might have lower absorption of B-vitamins that are produced in the hindgut. The addition of a balanced vitamin and mineral supplement may benefit these horses.

If your horse is losing weight because of chronic diarrhea, you may need to increase the energy density of your feeding program without adding starches which can exacerbate gut problems. This is best accomplished by adding sources of prebiotic, readily fermentable fiber such as soya hulls, linseed cake or whole flax seed, beet pulp or psyllium husk fiber.

Different horses have different needs. For these reasons, it is recommended that you work with a nutritionist to develop a balanced feeding plan optimized to meet the nutrient requirements of your horse.

2) Provide Plenty of Fresh Water

Horses that experience diarrhea lose excess water with their bowel movements and are at greater risk of experiencing dehydration. Sometimes, a horse that is dehydrated and not receiving sufficient salt will consume less water to maintain electrolyte balance.

It’s important to ensure that your horse is drinking enough water to replenish what they are losing with their fecal matter, to support gut health and to reduce the risk of colic</