Anterior Enteritis (AE) is an inflammatory disease of the small bowel of horses that causes colic and toxic shock. Recently the term duodenitis and proximal jejunitis has been substituted for anterior enteritis. Because of the severe pain and toxic-shock it often appears as a displaced bowel requiring surgery when medical therapy is best. In fact horses with AE often cannot survive surgery therefore it should be considered in all cases of colic and progressive shock. Fortunately there are some characteristics that help differentiate it from surgical colics.

AE used to be a common inflammatory disease of the small bowel and though the incidence seems to be declining it still remains a fairly common cause of colic case referral to larger equine hospitals where more aggressive therapy can be instituted. This article discusses the symptoms, diagnosis, causes, treatment, and prognosis of Anterior Enteritis in horses.

Acute colic, fever, depression, and darkened mucous membranes are always seen. The colic is characterized by high heart rates, decreased to absent bowel sounds, distended small bowel and perhaps most characteristic of all is a yellow-reddish foul smelling nasogastric reflux when tubed. The reflux can be a gallon or more and frequently when taken off the stomach the colic improves. Finding this characteristic reflux helps differentiate this disease from a small bowel twist or obstruction.

Other important differences in AE and those with a twisted small bowel are:

• A significantly greater proportion of horses with duodenitis/proximal jejunitis were older than 2 years old.
• Differences in sex or breed distribution, or in seasonality of the 2 disease syndromes were not observed.
• Horses with duodenitis/proximal jejunitis had significantly greater signs of depression than those with small intestinal obstruction
• Horses with small intestinal obstruction had significantly greater signs of abdominal pain.
• The mean heart and respiratory rates were significantly lower and the volume of nasogastric reflux was significantly greater in the group of horses with duodenitis/proximal jejunitis.
• Sections of small intestine that were palpable per rectum were less distended and there were more auscultable borborygmi in horses with duodenitis/proximal jejunitis, compared with those with small intestinal obstruction.
• The group of horses with duodenitis/proximal jejunitis had lower mean plasma potassium and higher mean plasma bicarbonate concentrations than the group with small intestinal obstruction. The mean nucleated cell count and total protein concentration of peritoneal fluid specimens were significantly less in the group with duodenitis/proximal jejunitis however, these values were greater than normal.