Abdominal palpation per rectum is highly sensitive for identifying small versus large intestinal lesions in horses presenting for colic

Objective: To describe the sensitivity, specificity, predictive values, and accuracy of abdominal palpation per rectum in horses treated surgically for colic. Methods: Medical records were gathered over 5 years (2019 to 2024). Findings of abdominal palpation per rectum were collected and compared to surgical diagnosis, and cases were categorized as true or false positive and negative. Signalment, physical examination parameters, hematologic values, and years of examiner experience were recorded. Results: Records of 453 horses were included. Overall sensitivity and positive predictive value were 86% and 79%, respectively. Specificity and negative predictive value were low at 5% and 7%, respectively. Accuracy (71%) was not different between small (72%) and large (70%) intestinal lesions. Small intestinal lesions were significantly associated with nonsurvival. There was no association between a correct diagnosis on abdominal palpation per rectum and short-term survival. Elevated heart rate, PCV, serum and peritoneal lactate concentrations, and age were associated with nonsurvival. There was no association between examiner experience and accurate diagnosis on palpation per rectum or patient survival. Conclusions: Abdominal palpation per rectum is highly sensitive for correctly identifying small intestinal versus large intestinal lesions in horses undergoing surgery for treatment of colic. Lack of association between examiner experience and accuracy or survival supports abdominal palpation per rectum at all levels of experience. Clinical Relevance: This study demonstrates an increase in accuracy of abdominal palpation per rectum compared to previous reports and supports its inclusion in the colic diagnostic plan when safe for the patient and examiner.