Antibiotic Associated Enterotoxemia in Guinea Pigs

Antibiotic-associated enterotoxemia is a condition in which the use of antibiotics results in a disruption of the normal intestinal flora. Pathogenic (disease causing) bacteria such as Clostridial organisms, overpopulate the intestinal tract and produce bacterial toxins, or enterotoxins, that cause blood poisoning and diarrhea.

Guinea pigs are herbivores (strict vegetarians) and have a similar digestive tract to horses, rabbits and chinchillas. Their digestive tract is specialized in order to help breakdown and digest plant materials. Most mammalian species do not have the digestive enzymes that are required to breakdown cellulose which is the main structural building block of plant material.

In order to accomplish this, guinea pigs have a storage organ called the cecum which is a pocket off of the intestines. This structure is equivalent to a human's appendix except that it is proportionally much larger in the guinea pig. The cecum serves as a storage organ that allows bacteria, digestive enzymes, and ingested food time to mix and breakdown the tough cellulose.

Periodically, the cecum empties the mixture into the intestinal tract where nutrients can be absorbed. Some nutrients (such as Vitamin B) are not absorbed until they go through a second pass, which is accomplished through copraphagy (eating of feces). Coprophagy is important and normal for guinea pigs.

Bacteria are important for the proper function of the digestive tract. The bacteria live in the intestinal tract in a symbiotic relationship, which means it benefits both the bacteria and the guinea pig, and any imbalance in the normal intestinal gut flora (bacteria found in the intestines) can have severe repercussions.

Antibiotics are often required to treat infections in guinea pigs. Their function is to kill or stop bacteria from reproducing. Because of the way they work, each antibiotic has a different spectrum or range of different types of bacteria it will affect. Using antibiotics can be dangerous because it can eliminate the normal intestinal flora and allow pathogenic (harmful) bacteria to flourish in its place, resulting in enterotoxemia.

What To Watch For

Typically, clinical signs if enterotoxemia begin 6 to 48 hours after beginning antibiotics. Common antibiotics that cause this condition are penicillins (amoxicillin and ampicillin), lincosamides (lincomycin and clindamycin), aminoglycosides (gentocin, amikacin), macrolides (erythromycin), and sometimes tetracyclines and cephalosporins (cephalexin, cefadrops).

Symptoms include:

• Diarrhea
• Lethargy
• Anorexia (no appetite)
• Borborygmus (gurgling of the intestinal tract)
• Hypothermia (low body temperature)
• Weakness
• Dehydration
• Listlessness

Guinea pigs generally succumb because of the toxemia (toxins in the bloodstream) and severe diarrhea causing dehydration and electrolyte imbalances that result in general organ failure. Also, due to the disruption of the intestinal normal defense, bacteria invade the blood stream and cause septicemia (systemic infection). Prognosis is very guarded. This is a very serious condition and most guinea pigs die despite aggressive therapy.

Diagnosis

Your veterinarian will probably recommend the following tests to aid in the diagnosis of enterotexemia:

• Microscopic tests. Fecal smears of the diarrhea can identify Clostridial organisms.
• Blood tests. A comprehensive panel can help identify other organ system failure and help direct proper treatment.

Treatment

• Fluids are a mainstay of the treatment. Severe diarrhea results in a large amount of fluid and electrolyte loss. Severe dehydration results in a drop in blood pressure which decreases the blood supply to major organs and contributes to the hypothermia and shock. Fluid replacement to treat the dehydration and low blood pressure can be given subcutaneously (under the skin), but many patients are too debilitated to absorb the fluids quickly enough to be helpful. A more successful route to administering fluids is an intravenous (in the blood vessel) or intraosseous (in the bone) catheter.
• Warmth is also very important. Sick guinea pigs expend a lot of energy fighting off infections and trying to stay alive. Providing warmth will reduce the amount of energy required to maintain their body temperature.
• Antibiotics are controversial. They are the reason the problem occurred in the first place, and yet they may help reduce the numbers of clostridial organisms which are producing the toxins.
• Analgesics (pain medications) help alleviate abdominal discomfort. Gastroenteritis will cause gas production and intestinal bloating which can be very uncomfortable. The pain causes guinea pigs to become anorexic and lethargic. The lack of ingested food and activity causes an ileus (slowing or stasis of the gastrointestinal tract) which allows for an increased absorption of the toxins. Banamine® (flunixin meglumine) is a good non-steroidal anti-inflamatory drug (NSAID) that is effective for gastrointestinal pain. Opiods (butorphanol, buprenorphine) are also used.
• Beneficial bacterial supplements, or probiotics, can be given both orally as a suspension or rectally as an enema to promote an optimum environment for the growth of normal gastrointestinal flora. There is some controversy as to whether this is helpful, but it does not cause any harm so is usually used.
• With severe enteritis, the intestinal bacterial flora can be replaced by feeding your sick guinea pig the normal stool of a healthy guinea pig, which is called transfaunation. It is not certain how much of the bacteria survive and make it to the intestinal tract since many are killed by the acid in the stomach. However, if any survive it will help recolonize and reestablish a normal population, as may using probiotics.
• Cholestyramine is a drug administered which helps bind enterotoxins and may help in severe cases of antibiotic associated enterotoxemia.
• Nutritional support is also critical. When stable enough, sick guinea pigs should be offered a variety of fresh foods to entice them to eat. If they refuse, then assisted or syringe feedings should be performed. Vegetable baby foods can be used or guinea pig pellet gruels can be made. There is a commercial herbivore critical care formula available for use as well.

Home Care

Once your guinea pig is out of the hospital and back at home, it is important to maintain the treatment protocol regimented by your veterinarian.

Good hygiene is very important. Your guinea pig will be predisposed to severe skin infections while they are having diarrhea or loose stools and it important to keep their rear ends clean.

Keeping them on a basic or bland diet (only fresh hay and small amounts of pellets with no treats) will help stabilize their gastrointestinal flora while it is reestablishing itself.

Preventive Care

Make sure you are seeing a veterinarian who is familiar with guinea pigs and will administer the "safer" antibiotics when they are required.

Probiotics can be given orally at the same time as the antibiotic regiment. Live culture yogurt works well and many guinea pigs will eat it like a treat. There are also commercial lactobacillus supplements that could be used.

While on antibiotics, avoid any sudden changes in your guinea pig's diet. Any changes can disrupt their normal gastrointestinal flora.