Ultrasonographic Assessment of Small Intestinal Motility Following Hyoscine Butylbromide Administration in Horses: A Pilot Study.
Authors: Haugaard Simon Libak, McGovern Kate F, Tallon Rose, Gough Rachel, Watrobska Natalia
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Hyoscine Butylbromide and Small Intestinal Ultrasonography in Horses Hyoscine butylbromide is routinely administered to horses with suspected colic prior to veterinary examination, yet uncertainty persists about whether this anticholinergic agent might obscure ultrasonographic findings and compromise diagnostic accuracy. This pilot study evaluated six hospitalised horses with medical colic and normal baseline ultrasound scans, using blinded assessment of small intestinal motility at three anatomical sites (right and left inguinal, hepatoduodenal window) before and repeatedly after intravenous hyoscine butylbromide at 0.3 mg/kg. Despite moderate interobserver variability in grading motility on the four-point scale, hyoscine butylbromide did not significantly suppress small intestinal motility at any location (P values ranging from 0.09 to 0.60) and critically, none of the horses developed the characteristic dilated, turgid intestinal loops associated with strangulating lesions. The expected tachycardic response occurred, with heart rate increasing significantly from a baseline of 33 ± 3 bpm to a peak of 71.3 ± 9 bpm one minute post-injection, remaining elevated for approximately 45 minutes (P = 0.04). For equine practitioners, these findings suggest that pre-hospital administration of hyoscine butylbromide should not compromise diagnostic confidence in ultrasonographic colic assessment, provided the examination occurs within a reasonable timeframe and visual landmarks of critical pathology remain identifiable.
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Practical Takeaways
- •Administering hyoscine butylbromide pre-admission for colic will not artificially create dilated loops on ultrasound or mask significant small intestinal pathology
- •The dramatic heart rate elevation (doubling within 1 minute) should be anticipated and monitored when using this medication in colic cases
- •Ultrasound examination performed shortly after hyoscine butylbromide administration remains valid for clinical decision-making in horses without pre-existing small intestinal disease
Key Findings
- •Hyoscine butylbromide at 0.3 mg/kg IV did not significantly reduce small intestinal motility on ultrasound at any location (P = 0.60 left inguinal, P = 0.16 right inguinal, P = 0.09 duodenum)
- •No horses developed dilated turgid small intestinal loops following hyoscine butylbromide administration despite moderate interobserver variability in motility grading
- •Heart rate increased significantly from baseline 33±3 bpm to peak of 71.3±9 bpm at 1 minute post-injection and remained elevated for 45 minutes (P = 0.04)