Diarrhea: Is It Serious?

Last Updated on August 21, 2023 by Allison Price

Learn how to distinguish between potentially fatal diarrhea and loose manure, as well as how to protect your horse from such conditions.

These four words from a client made my heart beat faster and my palms sweatier. It’s not what you expected. It’s not what you expected.

It’s simple. It’s simple. If diarrhea makes a client call the vet, it could be a sign that there is a sick horse in a barn with other horses at risk, or that it’s a more serious problem that will require a specialist to diagnose and treat. There’s a good chance that I will spend nights trying to find the best way to help.

Diarrhea can be difficult to diagnose and frustratingly difficult to treat. Diarrhea can be life-threatening and requires immediate treatment. Even if your horse is just suffering from diarrhea, it will still need to be treated.

This article will explain what diarrhea is and how it occurs. I will then explain the factors that can help determine if diarrhea is serious or just an annoying problem. Then, I will show you how to protect your horse and other horses in your herd from diarrhea.


What Is?

Diarrhea, an intestinal disorder, is characterized by frequent fluid manure evacuations. Your horse may poop a lot, which means that the poop is often messy, juicy, and wet. The horse may leave “cowpie” piles or pass what might appear to be normal poop, followed by a spray water, or in the worst case, “spray the walls with liquid.”

Why does diarrhea occur? Normal horse digestion starts the moment your horse puts food in his mouth. He chews to break down his food into smaller, more digestible pieces. Then he mixes the feed with saliva to buffer stomach acids.

After swallowing, the feed is sent to the stomach where it’s exposed and liquefied. The small intestine is where the first true absorption of nutrients starts. Simple sugars, amino acid (components protein) and vitamins and minerals can all be absorbed by the small intestine if the digestive tract is working properly. The large intestine functions as a fermentation vat. It is dependent on healthy populations of microorganisms (known as the microbiota), which help to break down large fibrous feed materials.

Volatile fatty acids are produced by fermentation in the large intestinal tract. These are vital sources of energy for horses, as well as vitamins and protein. The large intestine is also responsible for storing and absorption of water from ingested feed. The large intestine can absorb up to 30 gallons of water each day. Diarrhea is caused by a disruption in this function.

The large intestine’s ability to absorb water is compromised if it isn’t working properly. All that liquid will be eliminated in the manure. There are many ways to compromise the large intestine. Excessive consumption of carbohydrates can alter the pH (a measure acidity) and cause a disruption in the microbiota balance. Ingesting sand may cause damage to the intestinal cells.

Diarrhea can be a symptom but not a disease. Diarrhea can be a sign of a variety of diseases. These include mild gastrointestinal disturbances, severe, potentially fatal bacterial and viral infections. Mild, chronic diarrhea in some cases, such as an elderly horse with an aging digestive tract, can be perfectly normal. It is important to ask “How can you tell the difference?”


Five Key Question

Your vet will first try to determine if your horse has diarrhea that is “potentially fatal” or just a frustrating problem. The following five questions will help you decide.

1. Is he exhibiting fever symptoms? A fever is a temperature greater than 101.5 Fahrenheit that indicates your horse has an infection. It’s possible for his temperature to fluctuate throughout the day and may rise after exercising. After he has been quiet for at least 90 min, take his temperature. Your vet may be concerned if your horse has diarrhea-like symptoms.

2. Are there signs of discomfort in your horse? Does he look at his flanks or paw? Colitis is a condition where the horse experiences pain in his large intestine or colon. This is another sign that his symptoms are more serious and may require aggressive treatment.

3. How long has the diarrhea been going on? Did the diarrhea occur suddenly? If the diarrhea occurs suddenly, it is more serious. Chronic, low-grade diarrhea can be more concerning, even if your horse seems to be doing well.

4. Is he a victim? Although it may not seem obvious, horses who have been exposed to diarrhea infected other horses are at greater risk. If your horse is boarding in a facility where a diarrhea outbreak has occurred, it’s best to hope that the vet can determine the cause. According to estimates, only 30% of cases of severe colitis will be diagnosed with a definitive cause.

5. What can the lab work reveal? To fully assess the condition of your horse, your vet will likely recommend basic lab work. If your horse has a low white blood count or a significant decrease in protein, it may indicate that something is more serious. Your vet may order a fecal testing to determine if there is an infectious cause.

How to Do

Your vet will likely raise the alarm if you find out that your horse is having a serious health problem. Your horse will likely be admitted to the hospital and treated aggressively. To prevent life-threatening dehydration, intravenous fluids will be administered to your horse. Your vet will identify the underlying cause and guide you in your ongoing treatment.

What if your horse has diarrhea that is persistent and low-grade but he otherwise feels well? It’s unlikely you can find the root cause of your horse’s diarrhea in this situation. Instead, you will likely face a list with “can’t hurt but might help” management options, such as the following.

Change his diet. This is the most common cause of diarrhea, but it can be difficult to identify and treat. It is worth reducing the horse’s carbohydrate consumption. A horse that has too many carbohydrates can make it difficult for his small intestines to absorb simple sugars. A high carbohydrate intake can cause problems in the large intestine. Reduce or eliminate the use of cereal grains in horses’ diets, and avoid high carbohydrate hays.

Many vets who are “in the trenches,” believe that horses are sensitive to orchard grass hay. They recommend eliminating it from the horse’s diet. Consider removing all “necessary” items from your horse’s daily diet if orchard grass is not part of his diet. Reduce his diet to one type of hay, and a basic vitamin supplement. To help you identify the source of the problem, introduce one item at a time. This route should be followed with enough time between each change. It may take up to four weeks to notice improvements.

Take care of your horse’s medication. Diarrhea can be caused by both antibiotics and nonsteroidal anti-inflammatory drug (or NSAIDs), such as flunixin meglumine, flunixin meglumine or phenylbutazone. NSAIDs are used to reduce inflammation by blocking prostaglandins, a group of active lipid substances that can have different hormone-like effects on animals. NSAIDS can have a detrimental effect on the stomach and intestines. Some prostaglandins play a part in protecting the linings of the gastrointestinal tract. Chronic diarrhea is a well-known complication of long-term NSAID treatment.

Antibiotics can cause diarrhea by killing microorganisms which are essential to healthy, normal functioning of the large intestinal tract. These “good bugs” can be killed, and “bad bugs”, which can cause disruption and loss of normal functioning, may overgrow.

Ask your veterinarian if you should stop giving your horse any medication for diarrhea, especially NSAIDs and antibiotics.

Control parasites. Chronic diarrhea can be caused by parasite larvae that have burrowed into the horse’s intestinal walls. The current recommendations for a successful deworming program include regular monitoring and appropriate deworming. You should note that even if your horse has a low fecal count, they may still be suffering from heavy parasite burdens. The intestinal wall parasites that can cause diarrhea are not able to lay eggs. But don’t skip fecal egg counts! High egg counts are a sign of heavy parasite loads. Egg counts remain an important part of monitoring a successful control program. To determine if intestinal parasites may be causing diarrhea in your horse, you should discuss your control program with your veterinarian.

Balance microbiota. A serious cause of diarrhea can be an imbalance in normal, healthy bacteria found in the large intestine. What about probiotics. Probiotics are supposed to restore healthy gastrointestinal balance. Probiotics are not a must-have cure for chronic diarrhea. There is little research on the effectiveness of probiotics in horses. Also, there is not enough knowledge about the best formulation of “bugs.” These products aren’t subject to regulatory approval and can be sold as a dietary supplement or feed supplement. A probiotic must have the right amount of organisms. They must also be available in a form that can survive travel through the digestive tract and take up residence in large intestines. This is a lot to hope for. So what’s the bottom line? You can give probiotics to horses with chronic diarrhea if you wish. These products are generally safe. But don’t expect miracles.

Prebiotics: Prebiotics, which are supplements that support the health and well-being of existing microbes in the gut, are not like probiotics. These can include anything from psyllium, which is often used to clear the intestinal tract of sand, to large carbohydrate molecules called Oligosaccharides. They provide nutrition and support for healthy microbiota. Prebiotics are also included in yeast products, which most often contain portions of the organism Saccharomyces cerevisiae. Research has shown that yeast products have positive effects on existing microbiota. Prebiotics are not recommended for horses, as is probiotics. They “can’t hurt but might help” in most cases. However, some studies have suggested that they may be beneficial for horses with chronic diarrhea.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!