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.
Clinical relevance• This study describes the clinical presentation, case details and aetiology of horses suffering from a rare pathology, which could aid clinicians in diagnosing small intestinal intussusceptions more rapidly.• High complication rates after surgical correction of small intestinal intussusceptions should be expected, and those horses should be treated accordingly.• Long-term prognosis found in this study is good, and long-term complications are rare. This fact may help clinicians and owners in decision making.The study was accepted for presentation in part at the ECVS annual scientific meeting 2020.