Assessing gastrointestinal motility in healthy horses comparing auscultation, ultrasonography and an acoustic gastrointestinal surveillance biosensor: a randomised, blinded, controlled crossover proof of principle study.

Background: Auscultation and ultrasonography are noninvasive techniques used to assess gastrointestinal motility in horses. Recently, noninvasive acoustic gastrointestinal surveillance (AGIS) biosensors evaluating intestinal motility have been validated in humans.

Objectives: To compare AGIS to auscultation and ultrasonography for detecting decreased motility after xylazine administration.

Study Design: Randomised, blinded, controlled cross-over proof of principle study.

Methods: Six healthy horses were evaluated under fasted and nonfasted conditions and randomly assigned to receive treatment with 0.4 mg/kg xylazine or an equivalent volume of 0.9% NaCl intravenously. After a 48-h washout period, the process was repeated with the alternate treatment. Motility was assessed pre and posttreatment. Borborygmi were assessed in each abdominal quadrant and graded on a scale of 0-3, with 3 being continuous borborygmi. Duodenal, jejunal and caecal contractions were assessed ultrasonographically in consistent locations. Four AGIS biosensors were applied in standardised locations (duodenum, caecum, ventral midline, right dorsal colon). The biosensors measure acoustic signals and data were recorded in transport metric. Data were analysed using cross-classified multilevel random effects logistic regression including area under the receiver operator characteristic curve (AUC ROC). Sensitivity, specificity and accuracy were calculated for each modality.

Results: All three modalities detected a reduction in gastrointestinal motility following xylazine administration with AUC ROC being 0.85, 0.84 and 0.86 for auscultation, ultrasonography and AGIS respectively. The sensitivity, specificity and accuracy for auscultation was 88, 71 and 75%; for ultrasonography was 67, 63 and 64%; and for AGIS was 69, 70 and 70%, respectively.

Main Limitations: The study was performed in normal healthy horses and application of this device to clinical patients warrants further investigation.

Conclusions: In this proof of principle study, AGIS was able to discriminate between horses given xylazine from those given 0.9% NaCl with comparable accuracy as auscultation and ultrasonography. The Summary is available in Spanish - see Supporting Information.