Proximal Enteritis (Proximal Duodenitis/Jejunitis, Anterior Enteritis)
Dr. Melissa Mazan
Proximal enteritis is an inflammation of the first section of the small intestine and is a very serious cause of colic, or abdominal pain, in the horse. No one really knows what causes proximal enteritis. Some veterinarians suspect that there is a bacterial cause, but no single definitive cause has been defined. Loss of appetite
Some veterinarians report geographic areas where proximal enteritis is more common. It may have to do with the types of bacteria that naturally occur in certain locations. More cases seem to be seen in the southeastern United States.
Older horses are more susceptible to proximal enteritis, but it is also seen in young horses one to two years of age.
The inflammation causes the affected part of the intestine to malfunction. The intestine ceases to absorb fluids, and instead, large amounts of fluid accumulate in the intestine. The fluid accumulation causes the horse to become extremely dehydrated. Although he is undergoing continual water loss, it is futile for him to drink, because he can't absorb the fluid.
Because horses are unable to vomit, the fluid causes the intestines, and eventually the stomach, to swell and become extremely painful. Eventually, if this fluid build-up is not relieved, the stomach or intestines may rupture.
Proximal enteritis is easily mistaken for a surgical cause of colic, such as twisted small intestine. Even with the best of diagnostic equipment and skills, your veterinarian may not be sure whether your horse requires colic surgery. The signs of colic, reflux, and distended small intestine may go with either problem.
Although there are some differences in some cases of proximal enteritis, such as fever, slightly less pain than with a surgical colic, and far more reduction of pain after reflux, not all cases follow the book.
What to Watch For
Signs of abdominal pain (paw, roll, get up and down repeatedly)
Abrasions over the eyes or on bony areas of the body
Dry tacky gums
Lack of manure production
Lack of thirst
Increased respiratory rate
Lameness, warm feet
The most important diagnostic goal for your veterinarian is to determine if your horse can be treated medically or if the horse requires surgery. If your horse needs medical therapy, then your veterinarian will have to determine if therapy can be administered at home or if referral to an equine hospital is necessary.
Your veterinarian will perform a rapid but thorough physical examination, especially noting heart rate, respiratory rate, rectal temperature, and the presence of gut sounds.
Your veterinarian will reflux your horse, which is the use of a nasogastric tube to relieve distention of the small intestine. Horses with proximal enteritis, as opposed to a surgical cause of colic, will experience pain relief as long as the intestines and stomach are kept decompressed.
An rectal examination will determine if there are distended loops of small intestine.
Examination of the abdomen with ultrasound will detect small intestinal distention.
Abdominocentesis (belly tap) will detect signs of inflammation.
A compete blood count (CBC) may detect signs of infection or inflammation. This test is usually not available on an emergency basis to your veterinarian; results are usually not available until the next day.
A chemistry profile will look for signs of dehydration, electrolyte imbalances, and possible kidney problems secondary to dehydration. This test is usually not available on an emergency basis as results are usually not available until the next day.
A blood gas will help assess acid-base abnormalities.
Because it is can be very difficult, and sometimes impossible, to differentiate proximal enteritis from a surgical cause of colic, such as twisted small intestine, your practitioner will usually recommend referral to a facility that performs colic surgery. In some cases, an exploratory surgery is necessary to determine the cause of abdominal pain and reflux in your horse.
Proximal enteritis can be a very expensive disease, due to the high cost of intravenous fluids and nutritional support.
The most important, life-saving treatment is gastric and small intestinal decompression. This is done using an indwelling nasogastric tube and will have to be repeated frequently throughout the day and night.
Intravenous fluid therapy is imperative in countering dehydration.
Electrolyte imbalances can also be addressed with fluid therapy.
Antibiotics may or may not be given, depending on the individual case.
Anti-inflammatory drugs, especially Banamine, will help to make the horses more comfortable, and may counter inflammation.
If your horse develops laminitis, your veterinarian will pursue specific treatment for that problem. It is important to make sure that your horse is bedded comfortably in deep shavings, peat moss or sand.
Some veterinarians choose to treat with DMSO, heparin, pentoxyfylline, and acepromazine to counteract the effects of inflammation. Proximal enteritis usually requires many days of critical care treatment, and often requires hospitalization.
Horses with proximal enteritis may need intravenous nutritional support if the period of reflux lasts more than a few days.