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What is Anti-endotoxin Therapy?

Endotoxins are a byproduct of gram negative bacteria which are present in your horse's digestive system and normally aid in digestive processes. These endotoxins are released from the gram negative bacteria's cell walls when they die or as they multiply and cell walls break down. Under normal circumstances, these endotoxins are contained in your horse's bowel by an intestinal barrier that secretes mucus containing enzymes, and antibody secretions that also serve to contain these endotoxins. If small amounts of endotoxins migrate out of the intestinal area they are usually processed by the immune system. However, if your horse’s bowel system experiences imbalance and disorder, these gram negative bacterias can produce large amounts of endotoxin that overwhelm the system. Or, if an injury occurs that compromises the natural barrier to endotoxin release such as vascular disorder, surgical trauma, or peritoneal trauma, endotoxin can be released into your horse’s circulatory system. This can result in endotoxemia characterized by severe inflammatory response, gastrointestinal illness, colic, and septicemia. If endotoxins are released into your horse's circulation system causing severe disease, anti-endotoxin therapy must be conducted by your veterinarian immediately. There is a variety of medications and supportive treatments that can be administered to counteract endotoxemia and the resulting illness in your horse. Prompt treatment by a veterinarian is critical as this is a quickly progressing and life-threatening condition. Your veterinarian will address the cause of endotoxemic reaction, and then provide anti-endotoxic medications such as antiinflammatory agents and supportive medications.

Anti-endotoxin Therapy Procedure in Horses

The first approach to treating endotoxemia is to identify and treat the cause of endotoxin release which may be septicemia or colic related. Further anti-endotoxic treatment includes neutralizing endotoxins, decreasing inflammatory response, and providing supportive care.

  • Antibiotics may be used to treat septicemia but can further compromised gut flora resulting in widespread death of gram negative bacteria resulting in further endotoxin release.
  • Hyperimmune serum/plasma administered intravenously to neutralize endotoxins by reacting with them and preventing them from causing inflammatory response may be conducted. This requires administration prior to widespread circulation of endotoxins.
  • Administration of polymyxin B, an antibiotic that binds with lipid a therefore interfering with endotoxic processes, may be effective. However it presents a risk of neurotoxicity in horses and is also more effective if administer prior to endotoxic release although it can also be effective as toxicity progresses.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most common anti-endotoxin treatment, including flunixin meglumine (more effective for cardiovascular symptoms) and phenylbutazone (more effective for bowel motility issues) to counteract inflammatory response. They may be used in conjunction for maximum effect. Other NSAIDs may be administered as deemed appropriate by your veterinarian.
  • Fluid therapy to counteract dehydration and improve blood pressure in the heart and thereby reduce endotoxic activity in extremities will be provided.

Several experimental therapies are also being investigated and may also be used in the treatment of endotoxemia including; intestinal protectant DTO-smectite, ethyl pyruvate, phenyl methimazole, ketamine, pentoxifylline, pirfenidone, tyloxapol, phospholipid emulsions and omega 3 fatty acid infusion.



Efficacy of Anti-endotoxin Therapy in Horses

There are a variety of medications used to produce anti-endotoxin effects in horses with varying efficiencies. Effectiveness is greatly influenced by the timeliness of treatment and your veterinarian's ability to quickly identify the primary cause of endotoxin release and treat that condition. 


Prognosis for endotoxemia is guarded due to the severity of the primary cause of endotoxemia and the resulting medical condition. However use of anti-endotoxin therapies is critical to your horse's chance of survival if endotoxemia should occur. 



Anti-endotoxin Therapy Recovery in Horses

Prognosis is guarded. Recovery from endotoxemia can be complicated by organ damage sustained during endotoxemic episode or from side effects caused by various anti-endotoxin therapies. Your horse will require continued medication as directed by your veterinarian and careful monitoring of body temperature, gastrointestinal and fluid intake and output and general condition. Monitoring and follow up by your veterinarian will be required. In addition, any recovery from procedures required for the treatment of endotoxin release may complicate recovery. Rest and a modified diet will be recommended by your veterinarian, a slow careful return to normal feed and activity level will be necessary. 



Cost of Anti-endotoxin Therapy in Horses

The cost of anti-endotoxin therapy in horses varies widely depending on the ability to treat the associated cause and the type and extent of intervention required. In addition, management of endotoxemia conditions including critical organ systems such as the gastrointestinal system, respiratory system, cardiac, and circulatory system and can be costly. Treatment varies greatly depending on the requirements of each horse. As a result, the treatment for endotoxemia including anti-endotoxin therapies ranges from $1,000 to $6,000 or more with multiple variables present.



Horse Anti-endotoxin Therapy Considerations

Due to the serious nature of endotoxemia and associated medical conditions many complications and considerations exist. Various anti-endotoxin therapies are associated with various benefits and risks. 

In general, the earlier the therapies are administered the more effective. Several therapies have limited effect if not administered prior to endotoxin release into your horse's circulatory system.

Conditions such as dehydration, hypovolemia or neurotoxicity greatly complicate therapies and may contraindicate the administration of medications.

NSAIDs may make ongoing deterioration hard to detect as symptoms are masked and may impair intestinal functioning. The administration of lidocaine in conjunction with flunixin can prevent inhibition of gut functioning associated with that medication. 



Anti-endotoxin Therapy Prevention in Horses

When cleaning your barn, take stabled horses outside to prevent them from breathing in dust contaminated with gram negative bacteria from fecal materials. 

Careful monitoring of your horse for signs of distress or illness and immediate attention from a veterinarian will increase the success of addressing conditions before they are complicated by endotoxemia. 

Methods of preventing colic such as slow changes to feed or exercise regimes and limit of rich grain feed resulting in reduced gastrointestinal disorder will limit the incidence of endotoxemia requiring anti-endotoxin therapies. 

Mares that have just foaled should be observed to ensure that all postpartum tissues are passed and no afterbirth is retained that would result in a septic condition.



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