Segmental eosinophilic colitis: a review of 22 cases.

This research focuses on a study of 22 horses that were treated for colic at the University of Liverpool Equine Hospital. The unique facet of these cases was that the horses were found to have a specific type of partial blockage in their colons, caused by particular cellular inflammation, with no clear cause identified. Surgery was performed to address these issues, and for most horses, the recovery was successful, allowing them to return to their previous work and performance level.

Research Context

• The research took place at the University of Liverpool Equine Hospital, from 1992-1998, and involved examining cases of colic in 22 horses. Colic in horses refers to abdominal pain, which can have numerous causes including gastrointestinal problems. The chosen cases were unique in that these horses were found to have a type of partial blockage or obstruction in their colon, known as segmental mural lesion.

Medical Findings

• The horses in the study were found to have a partial obstruction of the large colon caused by a segmental mural lesion located in the left dorsal colon.
• It was determined that surgery was necessary based on findings from rectal examinations, which showed secondary impaction and mucosal oedema in the large colon, and the presence of high levels of neutrophils in peritoneal fluid samples taken from the horses.
• The surgical site of the affected colon segment presented oedema (excess watery fluid) and various changes to the serosa, the outermost layer of the colon, ranging from redness to well-defined necrosis (tissue death).
• In 16 of the horses, these pathological changes were serious enough to warrant partial resection, or removal, of the left colon.

Post-surgery Observations and Outcome

• Tissue analysis after surgery revealed different stages of mucosal (inner colon lining) necrosis, significant submucosal oedema, and infiltration of eosinophilic leukocytes (white blood cells that fight disease). The term “eosinophilic colitis” describes an inflammation of the colon involving an unusually large number of eosinophils.
• No specific cause was identified for these pathological changes.
• Out of the 18 horses released from the hospital, 16 were alive and well between three months to seven years after their surgeries, and were able to return to their previous type of work and performance levels.
• The remaining two horses had to be euthanized due to the return of colic symptoms, although no autopsy was carried out on these horses.

Interpretation

• The research indicates that surgery can effectively treat horses experiencing colic symptoms due to eosinophilic colitis and its related colon complications.
• Nevertheless, the root cause for the development of such lesions remains unclear, pointing to the need for more research in this area.