Endotoxin Shock

Endotoxin is a type of toxin produced by some bacteria. It is formed from part of the cellular structure of gram negative bacteria such as Escherichia coli, normally found in the colon. Endotoxin is released from dead bacteria. Little endotoxin is absorbed in the colon. Endotoxin produced and released from the small intestine can be absorbed and enter the body. Small amounts of endotoxin cause shock that can lead to death.

Endotoxins are released only upon disintegration of gram-negative bacteria cells. Endotoxins do not stimulate immune response in the body They function by activating a blood-clotting factor to initiate blood coagulation and by influencing the complement system.

Signs of Endotoxins

Endotoxins manifest their presence by the following signs: fever, weakness, and swelling of tissues. An affected animal may experience a dramatic decrease in blood pressure and lapse into coma. This condition, commonly called endotoxin shock, may accompany antibiotic treatment of diseases due to gram-negative bacteria because endotoxins are released when bacilli are killed by an antibiotic.

Endotoxins usually play a contributing rather than a primary role in the disease process. Certain endotoxins reduce platelet counts in the host and thereby hinder clot formation. Other endotoxins are known to increase bleeding.

Endotoxin Effects on the Liver

Endotoxin entering the body is carried to the liver, where it is inactivated. However, increased endotoxin levels makes it difficult for the liver to neutralize endotoxins which increases the risk of liver damage. This damage can be aggravated by the presence of other substances in the liver that may not be necessarily toxins such as drugs, minerals (iron, copper).

Cultures of lactobacillus are of no value in reducing the numbers of endotoxin-producing bacteria in the digestive system of dogs and cats.

Meat Meal Contaminants

Processed pet foods contain endotoxin. Manufacturers do not measure endotoxin levels in pet foods, however, possibly because the amounts are thought to be low. In humans with inflammatory bowel disease small amounts of endotoxin cause diarrhea by reducing colonic salt and water absorption. Endotoxin also increases colonic mucosal permeability which makes it easier for the absorption of endotoxin as well as other substances that can stimulate allergies.

Greater than 50% of meat meal can be contaminated with salmonella. Meat meals are highly contaminated with bacteria because their source is not necessarily slaughtered animals. Animals that have died because of disease, accidents, or natural causes are the source of meat meal. These bacteria produce endotoxin.

Processing pet foods containing meat meal by the expansion-extrusion methods kills bacteria. Cooking contaminated meat meal does not destroy endotoxin, however, so the final product contains the toxin that can cause disease. Nothing can be done to decontaminate the food containing endotoxin.

Effect of Diet on Endotoxin Production

The diet affects endotoxin production. When nondigestible cellulose or hemicellulose accumulates and ferments in the colon, aerobic bacteria (mostly coliforms) increase 100 to 1000 times. Most pet foods have high concentrations of undigestible matter thereby supporting aerobic bacteria growth better than other foods. Polished white rice contains low amounts of nondigestible fiber and is more completely digested than other sources of carbohydrate in pet foods. Including rice in diet reduces growth of colonic endotoxin-producing bacteria. Thus, it is the carbohydrate of choice in diets for treatment of digestive tract diseases in dogs.

A key element of endotoxin shock (also called gram-negative shock) is the presence in circulation of a variety of inflammatory agents. Endotoxemia (presence of toxins in the blood) results when one or more of many and varied "adverse contributing factors" interferes with normal liver functions, and/or results in increased endotoxin production within an increased absorption from the gastrointestinal tract so the detoxication is incomplete. Increased capillary permeability, with drastically decreased blood clotting levels, result in varying amounts of swelling and bleeding primarily in the lungs, where the greatest concentration of endotoxin occurs, and death.

Recent research suggests that in some dogs, certain genetic defects interfere with the process of containment of bacterial growth by the immune system causing diarrhea, swelling of tissues, bleeding, vomiting and fever.^1-2

References:
1. Home-prepared dog & cat diets: a healthful alternative By Donald R. Strombeck
2. Genetic Susceptibility to Infectious Diseases. Richard A. Kaslow M.D., Janet McNicholl M.D.
3. Alcamo's Fundamentals of Microbiology. Jeffrey C. Pommerville