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

Overview

• This study evaluated how accurately abdominal palpation per rectum identifies small versus large intestinal lesions in horses undergoing surgery for colic.
• The research assessed sensitivity, specificity, predictive values, and accuracy of this diagnostic method over a five-year period.

Background and Objective

• Colic, a common and potentially serious condition in horses, often requires rapid and accurate diagnosis to determine the affected intestinal segment (small or large intestine).
• Abdominal palpation per rectum is a common diagnostic technique used to identify lesions contributing to colic symptoms.
• The study aimed to measure the diagnostic performance—specifically sensitivity, specificity, predictive values, and overall accuracy—of abdominal palpation per rectum by comparing findings to surgical diagnoses.
• Additional factors such as horse signalment (age, breed etc.), physical exam parameters, hematologic values, and examiner experience were recorded and analyzed for their influence on diagnostic accuracy and survival outcomes.

Study Design and Methods

• A retrospective review of medical records from 453 horses that underwent surgery for colic, between 2019 and 2024.
• Data collected included results of abdominal palpation per rectum and confirmed surgical diagnoses to classify cases as true positive, false positive, true negative, or false negative.
• Signalment information, physical exam values (e.g., heart rate), laboratory results (e.g., packed cell volume (PCV), serum lactate, peritoneal lactate), and examiner experience level were also included.

Key Findings

• Sensitivity: High at 86%, indicating abdominal palpation per rectum is effective at correctly identifying horses with lesions (both small and large intestinal) during colic surgery.
• Positive Predictive Value (PPV): 79%, meaning a positive finding was likely to be a true lesion.
• Specificity: Low at 5%, signaling a high rate of false positives when the lesion is not present.
• Negative Predictive Value (NPV): Also low at 7%, meaning negative findings are unreliable to confidently exclude lesions.
• Overall Accuracy: 71%, no significant difference between small intestinal lesions (72%) and large intestinal lesions (70%).
• Survival Outcomes: Small intestinal lesions were significantly associated with nonsurvival.
• Correct diagnosis via palpation was not linked to short-term survival, indicating diagnostic accuracy did not directly influence immediate outcome.
• Higher heart rate, PCV, serum and peritoneal lactate levels, and older age were associated with worse survival outcomes.
• No significant correlation was found between the examiner’s level of experience and the accuracy of diagnosis or the horse’s survival.

Interpretations and Implications

• The study establishes that abdominal palpation per rectum is a highly sensitive diagnostic procedure for distinguishing between small and large intestinal lesions in colic cases.
• Despite low specificity and negative predictive value, it remains a valuable tool for initial diagnostics due to its ability to identify true positives effectively.
• The lack of a link between examiner experience and diagnostic accuracy suggests that this technique can be reliably used by veterinarians at varying skill levels, improving accessibility and consistency of care.
• Given the improved accuracy compared to previous studies, the findings support including abdominal palpation per rectum as a key component of the diagnostic workup for horses presenting with colic when it can be performed safely for both the horse and examiner.
• The data emphasize the importance of considering multiple clinical and laboratory factors when assessing prognosis and deciding on treatment, rather than relying on palpation findings alone.

Conclusion

• Abdominal palpation per rectum is an effective, sensitive, and practical diagnostic approach for identifying intestinal lesion location in horses with colic undergoing surgery.
• This method enhances veterinary diagnostic capability without needing extensive experience and should be integrated into colic assessment protocols, optimizing patient management and outcomes.