What is Endotoxemia?
A condition that may come after your horse struggles with an illness like colic, pneumonia or a severe infection, endotoxemia is a serious inflammatory response that can cause your horse’s vital organs to fail and circulatory system to collapse. Endotoxemia is a systemic disorder that is caused by your horse’s response to gram-negative bacteria.
Endotoxemia is a serious inflammatory response to gram-negative bacteria that can lead to vital organ and circulatory system failure.
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Symptoms of Endotoxemia in Horses
Should your horse develop endotoxemia, he may show the following symptoms:
- Dark mucous membranes (usual pink color become reddish or purplish near the line of your horse’s teeth)
- Increased heart and respiratory rate
- Intestinal shutdown
When endotoxins result from gram-negative bacteria and move past the interior of the bowel and are not eliminated, it can lead to endotoxemia.
Endotoxins are also present in certain environments where horses reside. Horse manure will usually have high amounts of gram-negative bacteria, making it easy for stabled horses to breathe in a significant amount of endotoxin. Inhaling the endotoxin, along with dust, can cause inflammation of their airway.
Causes of Endotoxemia in Horses
Many micro-organisms exist in the intestinal tracts of horses. In a healthy horse, there are microbes in the bowel that stop pathogenic bacteria from growing out of control. Gram-negative bacteria (which assists in breaking down fibrous feed) will release part of its cell wall upon multiplying and then the bacteria will die. The part of the cell wall that is released is known as endotoxin. Usually, bacteria are stopped from moving past the interior of the bowel by an intestinal barrier that includes epithelial cells, as well as enzyme and antibody discharge that will protect against endotoxin.
Even when small quantities of endotoxin travel through the mucosal barrier and into the liver there are immune cells that help to eliminate it. Should this natural system go awry in any way and there is a die-off of gram-negative bacteria, the release of endotoxin can lead to serious health problems. Endotoxemia occurs when endotoxin is able to get past the intestinal barrier and into your horse’s systemic circulation.
Diagnosis of Endotoxemia in Horses
Should you notice concerning symptoms in your horse you will want to have him examined by your veterinarian. A complete physical examination will be conducted and your veterinarian will request a complete blood count and an arterial blood gas analysis. With endotoxemia, the complete blood count will often show leukopenia and neutropenia. The arterial blood gas will typically show arterial hypoxemia and signs of metabolic acidosis.
It is very important to catch the problem early in order to address it and limit any damage to your horse.
Treatment of Endotoxemia in Horses
Nonsteroidal anti-inflammatory drugs, or NSAIDs, such as flunixin meglumine and phenylbutazone are key in treating endotoxemia, though they won’t completely resolve the cell damage that results from the inflammatory responses. Intravenous fluids will likely be administered to your horse to help with his treatment.
Your veterinarian will try to prevent the endotoxin from entering your horse’s circulation, as well as try to neutralize it and eliminate or reduce the production of inflammatory mediators, along with delivering supportive care. In addition, your veterinarian will try to control the primary disease that your horse is experiencing in order to treat (or even prevent) endotoxemia. In cases of disease within the gastrointestinal tract, your veterinarian may consider the following:
- Removing ischemic bowel
- Providing supportive care in cases of inflammatory bowel disease
- Administering mineral oil in cases of grain overload
Efforts to neutralize endotoxins may include the use of hyperimmune serum or plasma given intravenously; this typically is most beneficial if given before the endotoxin has accessed your horse’s circulation. Another option to neutralize endotoxin is to give your horse Polymyxin B, a cationic polypeptide antibiotic. Dimethylsulfoxide (DMSO) may also be helpful and it is often given for its anti-inflammatory effects.
Recovery of Endotoxemia in Horses
Should your horse experience endotoxemia, your veterinarian will focus on supporting him cardiovascularly and limiting the inflammation he is experiencing as soon as possible. It is important that you follow the recommendations of your veterinarian and attend follow up appointments to ensure the best outcome for your horse.
You can take steps to help your horse’s gastrointestinal tract remain stable so that he can avoid developing endotoxemia at all. This includes the following:
- Any feed changes that you make should not be sudden
- Increase the amount of fiber in his diet
- Provide several smaller meals daily rather than two large meals
- Should any illness occur, have your horse examined and the illness resolved so that it does not lead to endotoxins being released into his circulation
- Have your horse out of the stall when it is being swept and when manure is being removed
- Steam or soak hay should your horse be thought to be at risk for heaves and feed it to your horse immediately