The effects of slow infusion of a low dosage of endotoxin in healthy horses.

This research paper investigates the effects on healthy horses of a slow, intravenous infusion of a low dosage of endotoxin, focusing especially on contractions and blood flow in sections of the digestive system, and overall indicators of health.

Methodology

• The experiment involved slowly injecting an extremely low dosage of endotoxin into six healthy horses.
• The endotoxin dosage was a cumulative 0.03 microgram per kilogram of the horse’s body weight, infused over a period of 60 minutes.
• Using force transducers, the researchers monitored contractions in the duodenum, right ventral colon, and cecum of the horses.
• Lateral caecal arterial blood flow was also measured using transit time ultrasonic blood flow probes.

Findings

• No significant changes were observed in duodenal contractile activity after the endotoxin was infused.
• In contrast, the contractile activity in the right ventral colon decreased after the endotoxin was infused compared to after a saline solution was infused (control).
• Caecal body contractile activity was significantly lower than the control at various time intervals following endotoxin infusion.
• Similarly, caecal apex contractile activity was significantly lower than control at various time intervals following the end of endotoxin infusion.
• Blood flow in the lateral caecal artery was significantly lower than control at the end of endotoxin infusion and at several time intervals afterward.
• The average carotid arterial pressure was found to be significantly higher than control at various times after endotoxin infusion.
• Endotoxin infusion also resulted in a significant increase in heart rate, respiratory rate and body temperature.
• The decrease in caecal contractile activity was observed to occur before the body temperature increased.
• All the horses appeared depressed and developed redness in the mucous membranes.
• Four out of the six horses exhibited signs of abdominal discomfort, such as stretching, pawing, and kicking their own bellies.

Implications

• This study suggests that even a very low dosage of endotoxin, when slowly infused, can significantly affect digestive system contractions and blood flow, as well as overall indicators of health, in healthy horses.
• The observations made in this study could be useful for understanding the effects of endotoxins on larger animal species and potentially on humans as well.