What Is Endotoxemia In Horses And What Can You Do About It?

If your horse has had an illness such as colic or pneumonia or any other severe infection, he or she may be at risk of developing a very serious inflammatory response known as endotoxemia. This condition can cause failure and collapse of your horse’s circulatory system and vital organs, so it’s nothing to play around with. This systemic disorder is caused by the body’s response to gram-negative bacteria.

How Can You Tell If Your Horse Has Developed Endotoxemia?

After your horse has suffered a serious illness, you should watch him or her very closely. Look for these symptoms which may indicate the development of endotoxemia:

  • Your horse’s gum line may become dark red or purple, especially along the line of the teeth.
  • Your horse’s respiratory rate and heart rate may be unusually high.
  • You may notice that your horse seems to be in a great deal of pain.
  • Your horse may experience a general malaise or depression.
  • Your horse’s intestinal functions may shut down.
  • Your horse may exhibit inexplicable sweating.
  • Your horse may be chronically dehydrated.
  • Your horse may run a high fever.

What Causes Endotoxemia?

what causes endotoxemia

Endotoxemia is the result of gram-negative bacteria moving from the horse’s intestines to its bloodstream. This will cause systemic toxic conditions or endotoxemia.

Just as with all animals, a horse’s intestinal tract is filled with a wide variety of microorganisms. Healthy horses have defensive intestinal microbes that block the development of pathogenic bacteria.

Gram-negative bacteria in the right amounts are necessary in your horse’s digestive tract. These are the bacteria that naturally break down high-fiber feed such as hay. When these bacteria reproduce, they release a portion of the cell wall.

The portion of the cell wall released into the system is the endotoxin. In a healthy horse, this bacteria does not move outside of the bowel. There is an intestinal barrier containing antibodies, enzymes, and epithelial cells that protect the rest of the body from contact with endotoxins.

Even if very small amounts of endotoxins make their way past to mucosal membrane, the liver acts as a backup. Its immune cells go to work to eliminate this contaminant. If this natural defense is not working, and gram-negative bacteria die off in large numbers, endotoxins can then enter the system in large numbers. This can cause endotoxemia.

These endotoxins can also be picked up within the horses environment. For example, horse manure is filled with endotoxins. If your horse lives inside a stable, he is at risk for breathing in these contaminants. If your horse breathes in dust that is loaded with gram-negative bacteria, he is at great risk of inflammation of his airway.

How Will Your Vet Diagnose Endotoxemia?

how will your vet diagnose endotoxemia

If your horse begins exhibiting any of the listed symptoms, it is cause for concern. You should call your vet right away for a full physical exam. Your vet may need to call for a complete blood count (CBC). He or she may also order an arterial blood gas analysis.

If your horse is experiencing endotoxemia, the CBC will reveal neutropenia and leukopenia in the blood. The arterial blood gas analysis will reveal indications of metabolic acidosis and also arterial hypoxemia.

These are very serious conditions that can get out of hand very rapidly. This why it is extremely important that you contact your vet right away if your horse exhibits any of the symptoms of endotoxemia. This is especially true if your horse has recently experienced a health challenge such as colic.

How Do You Treat Endotoxemia?

how do you treat endotoxemia

Your vet may call for administration of NSAIDs (nonsteroidal anti-inflammatory drugs). Some examples are flunixin meglumine or phenylbutazone. These drugs don’t resolve cell damage, but they do reduce inflammation and this facilitates healing. Your vet will also probably call for administration of intravenous fluids to support this treatment and help prevent dehydration.

Your vet is also sure to take steps to help keep endotoxins from circulating throughout your horse’s system. This will involve reducing and neutralizing inflammation and providing supportive care.

Your vet may also reevaluate the primary disease that is causing the endotoxemia. Aggressive treatment of this root cause will naturally reduce the problem and may help prevent its recurrence.

If your horse has been struggling with a gastrointestinal tract disease, your vet may recommend some of these treatments:

  • If your horse has eaten too much grain, your vet may recommend administering mineral oil.
  • You may need to provide your horse with supportive care for inflammatory bowel disease.
  • The ischemic bowel may need to be removed.

To neutralize endotoxins, your vet might administer intravenous plasma or a hyperimmune serum. These treatments can be very effective if endotoxins have not yet entered your horse’s bloodstream.

Another way of neutralizing endotoxins is to administer a cationic polypeptide antibiotic called Polymyxin B. As a catalyst, dimethylsulfoxide (DMSO) can be very helpful in speeding delivery of anti-inflammatory medications. DMSO also has value as an anti-inflammatory substance on its own.

If your horse has endotoxemia, your vet will do all that he or she can to provide cardiovascular support and limit inflammation. These steps must be taken very quickly for best results.

Your vet will also make recommendations for ongoing care, and it is very important that you follow them to the letter even if your horse seems to have recovered fully.

Is It Possible To Prevent Endotoxemia?

Of course, the best way of dealing with endotoxemia is to avoid it altogether. There are many steps that you can take to help your horse maintain a healthy gastrointestinal tract. Follow these 6 smart tips:

  1. Always take your horse out of the stall when you are cleaning and moving manure around. This will help prevent your horse inhaling endotoxins.
  2. Remember that horses are grazing animals and can maintain a healthier digestive system by consuming many small meals throughout the day rather than eating one or two large meals a day.
  3. Do not make sudden feed changes. Add or reduce ingredients and feed gradually over a period of at least two weeks.
  4. Be sure your horses getting plenty of dietary fiber. He or she should have free access to high-quality hay at all times.
  5. If your horse is subject to heaves, be sure to soak or steam his hay thoroughly and feed it right away.
  6. If your horse becomes ill, don’t hesitate. Call your vet right away and address any illness your horse may have. Endotoxins thrive in horses who are not in optimum health.

Understanding your horse’s digestive system will help you create an appropriate plan to help keep your horse’s gastrointestinal system strong and healthy to avoid endotoxemia.

The Equine Digestive System

Nicky Ellis
Nicky has been an editor at Horses & Foals since 2017. Horses have been in her life from her earliest memories, and she learned to ride a horse when she was 5. She is a mom of three who spends all her free time with her family and friends, her mare Joy, or just sipping her favorite cup of tea.


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