Cervicothoracic (stellate) ganglion block in conscious horses.

This study examines the impact of performing a cervicothoracic ganglion block, which is a type of local anesthetic, on the cardiovascular and respiratory systems of seven adult horses, comparing the effects of the anesthetic being applied on one side (unilateral) versus both sides (bilateral).

Research Method

• The researchers used seven healthy adult horses for the study
• They applied an injection of lidocaine HCl, a local anesthetic, between the first and second ribs of the horse, in order to target the cervicothoracic ganglion (CTG)
• They then monitored and compared how the horse’s body responded under three different conditions: before the injection (baseline), after a unilateral CTG block, and after a bilateral CTG block

Findings

• After the CTG block, the horses demonstrated features of Horner’s syndrome (a nerve disorder affecting the face and eyes), increased skin temperature, and extensive sweating across the face, neck, and upper body
• There was a notable decrease in respiratory rate after the CTG block compared to the baseline data
• There was also a significant increase in both arterial oxygen and carbon dioxide levels, as well as an increased temperature under the skin at the neck and shoulder area
• No significant changes were observed in blood pressure, rectal temperature, arterial pH, bicarbonate, PVC, and total solid concentration, suggesting that these body functions remained stable
• Arterial oxygen tension was notably lower in horses that underwent bilateral CTG blockade compared to those that underwent unilateral CTG blockade
• The horses tolerated the unilateral CTG blockade well without any sedation

Potential Drawbacks

• The researchers found that if injections of the anesthetic into the CTG were performed too frequently (less than 2 hours apart), this could cause bilateral recurrent nerve paralysis and airway obstruction in the horses
• The test didn’t significantly change cardiovascular and respiratory values in four horses without cervicothoracic sympathetic blockade given the lidocaine in the right cervicothoracic region

Overall, these findings suggest that CTG blockade could have potential use in anesthetic procedures in horses but caution is required to prevent potential complications.