H&H explores an unusual colic case: idiopathic focal eosinophilic enteritis

“He was hurling himself to the ground,” recalls dressage rider Elli Darling of the day in March 2019 when Forever London developed colic caused by a rare condition called idiopathic focal eosinophilic enteritis (IFEE). “It’s scary with an 18.2hh horse in a normal sized stable.”

Elli was joined by London’s owner, Pat Pomp, and Harriet Easton MRCVS from local Suffolk practice Ryder-Davies & Partners. When an initial examination suggested more than mild medical colic, the gelding was transferred to Newmarket Equine Hospital (NEH). Suspicions proved correct when surgeons discovered the reason for London’s discomfort.

“This disease causes blockage of the small intestine, when bands of inflammatory tissue form in the intestinal wall,” says Fran James MRCVS, a surgeon at NEH. “These bands cause a narrowing of the lumen, the opening inside the bowels, which can create a slowdown of the passage of food or a total obstruction.

“As the small intestine becomes obstructed, the normal contents back up to fill the upper part of the small intestine and stomach,” says Fran. “This can lead to life-threatening consequences. The distended small intestine may twist around itself, cutting off the blood supply to the affected segment, or the obstruction may cause the stomach to fill with material.

“Horses do not usually vomit,” she adds. “Without the passage of a stomach tube to release the accumulation of fluid, the stomach can rupture. Sadly, this is fatal.”

Saving London’s life

Upon London’s arrival at the hospital, an abdominal ultrasound followed by rectal examination revealed multiple, distended loops of small intestine. Surgical exploration of the abdomen was the only way to correct whatever was causing the obstruction.

“We noted infiltration of the small intestinal wall with inflammatory cells in several locations,” says Fran, explaining that inflammation and damage is caused by excessive accumulation and activation of eosinophils (one of the less common types of white blood cell) within the intestinal wall. “The lesions were of variable size, the largest appearing as an area of reddish thickening which extended like a ring around the circumference of the intestine.

“Based on the appearance of the bowel wall, we suspected a diagnosis of idiopathic focal eosinophilic enteritis,” she adds. “The lesions were too numerous to remove surgically, so we immediately started corticosteroid treatment that would continue into the post-operative period. We then broke down the obstruction by manipulating the material and ‘milked’ the contents into the large intestine.”

“Subsequent analysis of biopsy samples taken from the bowel wall confirmed active eosinophilic inflammation, consistent with idiopathic focal eosinophilic enteritis,” adds Fran.

More complications

Although clear of immediate danger, London required careful nursing through the critical post-operative period.

“As with many routine, small intestinal colic surgeries, we administered intravenous fluids, broad-spectrum antimicrobials and anti-inflammatory treatment,” says Fran. “London also received an intravenous continuous rate infusion of lidocaine, to promote a return of intestinal motility [movement]. We restricted all food and water and monitored him closely.”

About 48 hours after surgery, London showed a recurrence of colic signs. While the team could not rule out re-obstruction at the original site, the fluid collecting in his small intestine and stomach might also indicate a complication, such as post-operative ileus (POI) – where the intestine fails to regain normal function.

“POI can be prolonged or will fail to fully resolve, necessitating euthanasia,” says Fran. “Repeat surgery may be unsuccessful and is not always an option.

“Another danger is the development of adhesions, which form when the outermost layer of the intestine, known as the serosa, is damaged,” she adds. “This makes the surface ‘sticky’ and vulnerable to becoming attached – temporarily, at first – to adjacent structures in the abdomen. Left undisturbed, early adhesions mature into permanent scar tissue over the subsequent seven to 10 days, with the potential to cause an obstruction of the intestine.”

Fran explains that the longer the initial period of obstruction, the greater the complications.

“All steps that can be taken to limit the degree of damage to the intestine will minimise the potential risk of adhesion formation,” she says, stressing the importance of rapid and accurate diagnosis and treatment.

“As the intestine becomes inflamed, due to an obstruction or secondary to the blood supply being interrupted, the bowel wall may become damaged. As long as this episode is short lived, a potential cascade of inflammatory response is minimised and normal intestinal function can begin again once the obstruction or strangulation is corrected.

“Handling of the bowel during surgery may add to the inflammatory response, so we are careful to limit disturbance as much as possible,” she adds.

Thankfully, London’s gastrointestinal function improved over the next 12 hours and he was allowed small quantities of water. His small intestine and stomach were monitored with ultrasound for a further 48 hours, during which time he was introduced to easily digested feed and the addition of some fresh-cut grass.

“He began to pass normal droppings, while maintaining his appetite, and was fed little and often as hay was reintroduced and concentrates increased to normal amounts,” says Fran.

“Following good progress, he was switched to an oral anti-inflammatory treatment to be administered at a progressively tapering dose for a further month.” And 10 days after surgery, London was discharged from hospital.

About idiopathic focal eosinophilic enteritis

Idiopathic focal eosinophilic enteritis is part of a group of inflammatory bowel diseases.

“It is not a well-understood condition and for the time being remains idiopathic, meaning that its cause or trigger is not known,” explains Fran.

“Intestinal parasites have been regarded as a cause, but the majority of horses that suffer from this condition have a good worming history – as was certainly the case with London,” she says.

“An allergic response to food substances is thought to be behind a similar condition in humans, but there has been no direct indication of this in equine patients. Another theory is a potential overreaction by the immune system, with activation of eosinophils.”

The prognosis for horses surviving idiopathic focal eosinophilic enteritis is generally good, Fran explains.

“From published studies, and based on my own personal experience, many cases make an excellent recovery following the course of corticosteroid treatment, which is aimed at resolving the excessive inflammatory response.

“It is fortunate that the early stages of London’s colic were recognised and that the vet who referred him to NEH was immediately aware of the severity of his problem,” adds Fran.

Living it large

During his lengthy rehab at Elli’s yard, London behaved impeccably.

“He’s a quirky horse but he was textbook throughout, which was a relief with him being as big as he is,” says Elli. “The operation site on his abdomen was small and healed quickly, so he didn’t really lose his tummy muscles. However, it has taken a long time to build him back up.”

London was able to return to ridden exercise after three months and in August, he made a competition comeback to finish third in the Bicton Arena summer regionals. A year on, and “twice the size, bulk-wise” according to Elli, he is winning at elementary and ready for medium.

The author: Fran James MRCVS is a surgeon at Newmarket Equine Hospital. This purpose-built referral hospital is one of the largest in Europe, treating a wide range of horses from throughout the UK. Fran is a Royal College of Veterinary Surgeons (RCVS) specialist in equine surgery and has a particular interest in equine orthopaedics and causes of poor performance in equine athletes (newmarketequinehospital.com/01638 782020).

Ref Horse & Hound; 16 April 2020