Evaluation of continuous infusion of lidocaine on gastrointestinal tract function in normal horses.
Authors: Rusiecki Karen E, Nieto Jorge E, Puchalski Sarah M, Snyder Jack R
Journal: Veterinary surgery : VS
Summary
# Lidocaine Infusions and Equine Gut Motility: What Clinicians Should Know Continuous lidocaine infusion, commonly used in equine practice for analgesia and anti-inflammatory effects during colic management, significantly slows gastrointestinal transit in healthy horses. Researchers administered barium-filled microspheres to six horses via nasogastric tube and tracked their passage through the digestive tract, comparing a three-day lidocaine infusion protocol (1.3 mg/kg bolus followed by 0.05 mg/kg/min continuous infusion) against saline controls using radiography and faecal collection. The lidocaine group showed a marked delay in transit: whereas control horses passed 50% of microspheres within 42 hours, the lidocaine-treated group required 50 hours, and faecal output during the first 24 hours dropped from 15 kg to 10.8 kg. This finding carries serious clinical implications—particularly for horses presenting with impaction colic or undiagnosed abdominal pain, where decreased motility could worsen outcomes, and in cases where lidocaine is combined with other pro-stasis medications. Practitioners should carefully weigh the analgesic and anti-inflammatory benefits of continuous lidocaine infusion against its prokinetic costs, ensuring appropriate diagnosis before treatment and considering dose reduction or alternative analgesia in at-risk cases.
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Practical Takeaways
- •Avoid continuous lidocaine infusion in horses with suspected colic or impaction, as it slows intestinal transit and could worsen these conditions
- •If using lidocaine infusions in clinical cases, monitor fecal output closely and be cautious when combining with other prokinetic-suppressing medications
- •Consider the 8+ hour delay in transit time when using lidocaine infusions; this effect may mask or complicate diagnosis in horses with unknown colic
Key Findings
- •Continuous lidocaine infusion (0.05 mg/kg/min for 3 days) increased fecal transit time: 50% of barium microspheres passed at 50±1.32 hours versus 42±1.13 hours in controls
- •Fecal output in the first 24 hours of lidocaine administration was reduced to 10.8±6.9 kg compared with 15±4.9 kg in saline controls
- •Lidocaine administration decreased gastrointestinal motility as evidenced by delayed intestinal transit without reported signs of systemic toxicity