Epidural migration of new methylene blue in 0.9% sodium chloride solution or 2% mepivacaine solution following injection into the first intercoccygeal space in foal cadavers and anesthetized foals undergoing laparoscopy.

The research explored the correlation between epidural cranial migration (movement of a substance from the base to the head) and the volume of an isotonic solution containing dye injected into foal cadavers and anesthetized foals. It revealed increasing cranial migration with a rise in injection volume, and no significant variation between foal cadavers and those undergoing laparoscopy. The study also suggested that an epidural injection of 2% mepivacaine alone could provide adequate analgesia for caudal laparoscopic procedures in foals.

Research Objective and Methods

• Researchers aimed to establish the connection between cranial migration of a solution and the volume of the solution injected. The experiment used foal cadavers as well as anesthetized foals undergoing laparoscopy, a minimally invasive surgical procedure.
• The cadavers were injected with dyed solutions of varying volume, and the length of the dye column and number of intervertebral spaces were then measured.
• The anesthetized foals were injected with a dyed solution and were then placed in a 100 head-down position, and a pneumoperitoneum (abnormal presence of air or gas in the cavity between the lungs) was induced.
• Dermatome analgesia, i.e., the numbness produced by the injection, was calculated using an electrical stimulus method. The length of the dye column was measured after euthanizing the foals.

Research Findings

• It was found that the cranial migration of the dye solution increased as the volume of the injected solution increased in the foal cadavers.
• During laparoscopic conditions, the cranial migration of the dye solution in the anesthetized foals was not significantly different from that in the foal cadavers.
• Dermatome analgesia didn’t indicate the full extent of dye column’s migration towards the head; the dye solution spread further than the area of numbness.

Research Conclusions

• The research concluded that the cranial migration of an epidural solution increases with the volume of the injection.
• Dermatome analgesia showed that an epidural injection of 2% mepivacaine alone offers sufficient analgesia, making it possible to carry out caudal laparoscopic surgical procedures in foals.