Evaluation of continuous infusion of lidocaine on gastrointestinal tract function in normal horses.

The research article investigates the impact of continuous infusion of the local anesthetic lidocaine on the digestion, specifically the fecal transit time, in healthy horses. The researchers found that lidocaine increases the transit time of feces, highlighting its potential to worsen the effects of drugs that decrease motility or cases of medical colic in horses.

Objective and Methodology

• This experimental randomized cross-over study aimed to determine if the analgesic drug lidocaine would affect the time it takes for food to pass through the digestive system in healthy horses.
• Six horses were used in the study, with barium-filled microspheres administered via nasogastric intubation and feces collected every 2 hours for 4 days.
• The horses were first given a bolus of 2% lidocaine, followed by 0.05 mg/kg/min of lidocaine continuously for 3 days, or an equivalent amount of saline for the control group. A washout period of 10 days was observed between the different treatments.
• The researchers evaluated a number of variables to assess the impact of lidocaine, including defecation frequency, weight of feces, intestinal transit time, fecal moisture content, and heart and respiratory rate.

Results

• The results showed that, compared to the control group, lidocaine reduced fecal output and increased the time it took for half of the barium-filled microspheres to be passed.
• Fecal output was observed to fall to 10.8 kg with lidocaine compared to 15 kg in the control group during the first 24 hours of lidocaine administration.
• Moreover, it took 50 hours for horses in the lidocaine group to pass 50% of the microspheres compared to 42 hours in the control group.

Conclusions

• From the observations, the researchers concluded that continuous infusion of lidocaine slows down the transit of feces through the horse’s digestive system.
• This implies veterinarians ought to be aware of potential complications when using lidocaine, especially in conjunction with other drugs that decrease motility, or in cases where the horse is already suffering from digestive issues such as impaction or undiagnosed medical colic.