Effect of ligation on internal carotid artery blood pressure in horses.

The research article investigates the impact of ligature or tying off the internal carotid artery in horses on blood pressure levels. Contrary to the expected outcome, the pressure remained unaffected post-ligation, emphasizing the need for alternative treatment pathways to prevent severe hemorrhage in horses with guttural pouch mycosis.

Research Methodology

• The study involved experimentation with nine horses. The researchers injected a single ligature on the internal carotid artery of the horses and monitored the subsequent changes in blood pressure.
• The internal carotid artery of six anesthetized horses was catheterized at 2 cm from its origin, and the pre-ligation blood pressure was recorded. Post-ligation, the researchers recorded the blood pressure again, following which the horses were euthanized.
• In three additional horses, indwelling catheters were placed in both internal carotid arteries, and a loose ligature was situated proximal to one catheter. After the recovery of the horses from anesthesia, blood pressure measurements were recorded post ligature tightening, on the day of the procedure, and three days later.

Outcomes of the Study

• The anatomy of the cerebral arteries was examined in all the horses. Contradictory to the anticipated outcome, the blood pressure in the ligated internal carotid arteries remained unchanged.
• According to the subjective observations, the most probable collateral channels that could potentially maintain the blood pressure in the tied-off internal carotid artery were identified as the caudal intercarotid artery and the cerebral arterial circle.
• The key finding of this report was the conclusion that ligation of the internal carotid artery would not effectively forestall severe hemorrhage from the internal carotid artery in horses suffering from guttural pouch mycosis, unless the ligated artery thrombosed up to the lesion level.

Implications of the Research

• This research study serves to challenge the existing assumption of ligatures reducing blood pressure in ligated arteries, highlighting the complexities of the equine circulatory system.
• The discovery implies that alternative, more effective treatments or interventions are required to prevent severe hemorrhage in horses with guttural pouch mycosis, as standard ligation techniques do not seem to perform satisfactorily.