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.
OBJECTIVE
To determine the relationship between epidural cranial migration and injectate volume of an isotonic solution containing dye in laterally recumbent foal cadavers and evaluate the cranial migration and dermatome analgesia of an epidural dye solution during conditions of laparoscopy in foals.


METHODS
19 foal cadavers and 8 pony foals.


METHODS
Foal cadavers received an epidural injection of dye solution (0.05, 0.1, 0.15, or 0.2 mL/kg) containing 1.2 mg of new methylene blue (NMB)/mL of saline (0.9% NaCl) solution. Length of the dye column and number of intervertebral spaces cranial and caudal to the injection site were measured. Anesthetized foals received an epidural injection of dye solution (0.2 mL/kg) containing saline solution or 2% mepivacaine. Foals were placed in a 100 head-down position, and pneumoperitoneum was induced. Dermatome analgesia was determined by use of a described electrical stimulus technique. Foals were euthanatized, and length of the dye column was measured.


RESULTS
Epidural cranial migration of dye solution in foal cadavers increased with increasing volume injected. No significant difference was found in epidural cranial migration of a dye solution (0.2 mL/kg) between anesthetized foals undergoing conditions of laparoscopy and foal cadavers in lateral recumbency. Further craniad migration of the dye column occurred than indicated by dermatome analgesia.


CONCLUSIONS
Epidural cranial migration increases with volume of injectate. On the basis of dermatome analgesia, an epidural injection of 2% mepivacaine (0.2 mL/kg) alone provides analgesia up to at least the caudal thoracic dermatome and could permit caudal laparoscopic surgical procedures in foals.
Lansdowne
Jennifer L
JL
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Kerr
Carolyn L
CL
Bouré
Ludovic P
LP
Pearce
Simon G
SG
D000767:Anesthesia, Epidural / Q000662:veterinary*; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000493:pharmacokinetics; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D004396:Coloring Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D004824:Epidural Space / Q000378:metabolism*; D005260:Female; D006736:Horses / Q000378:metabolism*; D007268:Injections, Epidural / Q000662:veterinary; D010535:Laparoscopy / Q000662:veterinary; D008297:Male; D008619:Mepivacaine / Q000008:administration & dosage*; D008751:Methylene Blue / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D011187:Posture
D000779:Anesthetics, Local; D004396:Coloring Agents; C035184:new methylene blue; D008619:Mepivacaine; D008751:Methylene Blue