Small intestinal intussusception in horses: Multicentre retrospective report on 26 cases (2009-2020)

Background: Intussusception is an infrequent cause of equine colic, most commonly encountered in young horses. This condition occurs due to abnormalities of motility and frequently includes the caecum. Objectives: The purpose of this study was to review the cases of equine small intestinal (SI) intussusception excluding those with caecal involvement. Study design: Case series, analytical retrospective study. Methods: Medical records of all horses that had SI intussusception, not involving the caecum, from three equine clinics between 2009 and 2020 were reviewed. Information obtained included: clinical parameters, surgical or necropsy findings, complications and outcome. The Mann-Whitney U test was used to compare the outcome and complications with various parameters. Fisher’s exact test was used to compare short-term survival with categorical variables. Significance was set at p ≤ 0.05. Results: Twenty-six horses met the inclusion criteria. Median age of horses was 9 months (interquartile range 2.8 months–6.5 years). Relevant history included diarrhoea and general anaesthesia. Twenty-two out of 26 horses were diagnosed during surgery and 4 at necropsy. During surgery, 5 horses were subjected to euthanasia, 9 underwent manual reduction and 8 underwent resection and anastomosis. The postoperative complication rate was high at 47% and included ileus, diarrhoea and colic. The prognosis decreased when the involved segment was longer (p = 0.032), lactate levels were higher (p = 0.024) and reflux was present before admission (p = 0.024). Of all horses, 53% survived to discharge and 92% of these survived for >1 year post-operatively (one case was lost to follow-up). Main limitation: The retrospective nature of the study and the low number of cases included. Conclusions: Small intestinal intussusception was diagnosed in horses of a variety of breeds and ages. Alterations of motility can predispose to intussusception, not only due to hypermotility (diarrhoea), but also due to hypomotility (anaesthesia). Prognosis for hospital discharge was fair; however, following hospital discharge, the long-term survival rate is high and complications are rare.