Abdominal Pain in Foals (AAEP 2003)

Abdominal pain in the foal can have many different causes, making it difficult to diagnose a cause. However, with knowledge of the different causes, a proper physical exam, the use of diagnostic tools, and common sense, a veterinarian can pinpoint a diagnosis from which decisions on treatment can be based, said Bill Bernard, DVM, Dipl. ACVIM, of Rood and Riddle Hospital in Lexington, Ky., during his presentation "Assessment of Abdominal Pain in Foals" at the 2003 American Association of Equine Practitioners' convention.

The need for a quick diagnosis is imperative, said Bernard. If surgery is necessary, the time from the onset of problems to surgery can make a difference in the outcome. "If, however, the decision for surgery is made without careful consideration of 'non-surgical' conditions, the outcome may be compromised by an unnecessary procedure," said Bernard.

The age of the foal can alert the practitioner to what might be causing the problem. The owner will be asked for a complete history on the foal, including questions such as:

� Has the foal had any problems such as fever or diarrhea?
� Has the foal had any previous medical problems or is he on any medications, such as antibiotics, that could predispose him to abdominal pain?
� Have there been any changes in management or feeding practices?

In addition to learning the history of the foal, the practitioner will do a physical examination, and use diagnostic tools such as radiography or ultrasonography. "When conditions allow," said Bernard, "observation of the patient from a distance is an invaluable portion of the physical exam."

An examination might rule out other causes for signs of pain such as musculoskeletal, neuromuscular, or neurologic disorders. Bernard pointed out that the foal is not as tolerant of pain as an adult horse, therefore signs of severe pain might not necessarily indicate a severe problem.

However, he said, "Persistent pain that is non-responsive to analgesics (pain-killers) is more consistent with a surgical, usually strangulating, lesion."

When differentiating between a surgical or non-surgical disease, vital signs might not allow for a definitive diagnosis. Blood work, abdominocentesis (puncture of the abdomen to evaluate peritoneal, or abdominal cavity fluid), nasogastric intubation to evaluate fluid from gastric reflux, gastroscopy to search for gastric ulcers, radiography, and ultrasonography can give valuable clues as to the cause of the abdominal pain.

More Common Causes
Bernard discussed the most common causes of abdominal pain in the foal in-depth, and also listed several of the less common causes of pain.

Some of the more common causes include meconium retention, enterocolitis, external or internal herniation, uroperitoneum (the presence of urine in the abdominal cavity), and small intestine volvulus (twisting or displacement). Meconium, the first stool of the newborn, is considered to be retained if it has not passed within 48 hours after birth. A diagnosis can be made through the use of contrast radiography with a barium enema. Abdominal pain can be mild to severe, he said.

Enterocolitis involves inflammation of the small intestine and colon. It can be characterized by diarrhea; however, diarrhea is typical in 70-80% of foals, usually during the first few weeks of life. Infectious agents are the most common cause of enterocolitis. Pain can be mild and brief, or in acute cases, pain can be severe and progressive.

The most common type of external herniation (protrusion of a loop of an organ or tissue through an abnormal opening) is seen as an umbilical hernia or an inguinal (pertaining to the groin) hernia. Diaphragmatic hernias (protrusion through the thin muscle that separates the chest from the abdomen) can result from a blunt trauma or from fractured ribs, said Bernard. Other types of internal herniations can include those of the gastrointestinal tract.

Uroperitoneum can result from a ruptured bladder or urachus (the cord from the bladder to the umbilicus). Bernard recommended the foal undergo electrolyte and peritoneal creatinine analysis and abdominal ultrasound examination for a diagnosis.

A foal with volvulus of the small intestine shows signs of severe, progressive abdominal pain that does not respond to analgesics (painkillers). If the problem has been going on awhile, the foal might be down or in cardiac collapse. Ultrasonography can aid in diagnosis.

Less Common Problems
Ileus occurs when gastrointestinal contents stop moving and the bowel becomes distended (swollen). "Ileus is particularly life-threatening in the neonate or weak foal," said Bernard. He recommended that radiographs and abdominal ultrasound be done if this is suspected.

Gastric outflow obstruction (blockage of food from exiting the stomach) is diagnosed with contrast radiography; surgery can correct this problem. Another problem needing surgery is an intussusception, which is when the intestine telescopes back into itself or into the cecum.  This can result in swelling, compromised vascular (blood) supply, and mild to severe abdominal pain.

Necrotizing (tissue-killing) enterocolitis results from hypoxemia (low blood oxygen levels) or ischemia (decreased oxygen due to a lack of blood supply) of the bowel wall. Surgical resection of the affected areas is necessary, said Bernard.

Strangulating lesions of the large colon (large colon volvulus) are not as common in foals as adult horses, since fermentation in the large bowel of the foal has not reached adult capacity, said Bernard. "Diagnosis is based on the degree and persistence of pain and observations of large bowel distention through radiography or ultrasonography," he continued.

Another problem with the foal's colon is displacement. This is rare in the foal, and it is not as serious as strangulating lesions.

A hot topic in the equine world is the problem of gastric ulcers. Foals are susceptible to gastric ulcers, resulting in mild to severe abdominal pain. Diagnosis is made through gastroscopy. Treatment includes medications called proton pump inhibitors or anti-secretory drugs.

Peritonitis, or inflammation of the lining of the abdominal cavity (peritoneum), can cause acute disease with signs of shock, or chronic disease, with signs of mild or intermittent pain. A veterinarian can examine the peritoneal fluid through abdominocentesis. Ultrasonography is also useful to find echogenically abdominal fluid.

It is important to be aware that a heavy ascarid (roundworm) infestation can cause small intestine impaction. Ultrasound can help the veterinarian visualize the infestation, or gastric reflux might contain ascarids. Surgery is usually required.

Bernard closed by saying that ovarian torsion, fecaliths (hard masses of dried feces), intestinal atresia (closure), and ileocolonic aganglionosis (a lack of nerve cells in the ileus and colon) were uncommon causes of abdominal pain in the foal.

About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

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