Lactic acidosis and arterial hypoxemia during sublethal endotoxemia in conscious ponies.

The research investigates the effects of a sublethal dose of Escherichia coli endotoxin on horses, recording symptoms like arterial hypoxemia, colic and diarrhea, as well as metabolic acidosis. This study is conducted over a span of 180 minutes.

Research Methodology

• For this study, seven conscious ponies were chosen as subjects. Conscious subjects were preferred to observe the physiological and symptomatic effects of the endotoxin.
• An intravenous dose of Escherichia coli endotoxin, calculated at 10 micrograms/kg of body weight, was administered. The dosage was sublethal, meaning the amount was not enough to cause fatality but sufficient to induce symptoms.
• Over a period of 180 minutes, arterial blood gases and plasma lactic acid levels were periodically checked and recorded. This helped in monitoring the change in these parameters over time in response to the endotoxin administration.

Observations and Results

• Arterial hypoxemia occurred in all ponies within the first five minutes of endotoxin administration. Hypoxemia refers to the reduced level of oxygen in the blood. Despite the ponies hyperventilating—an expected body response to maintain oxygen levels—they still experienced insufficient oxygen in the bloodstream.
• Symptoms of colic and diarrhea manifested in all ponies within the first 30 minutes after endotoxin administration. These symptoms are signs of the body reacting to the harmful effects of the endotoxin.
• Metabolic acidosis – a condition characterized by excessive acidity in bodily fluids due to the buildup of lactic acid, and indicative of reduced tissue perfusion—was observed to develop within the first 30 minutes post-administration, and persisted throughout the study period. This observation suggests that the endotoxin caused widespread reduced blood flow to tissues, contributing to an increase in lactic acid levels.

Conclusion

• This research provides important insights into the physiological responses exhibited by horses when exposed to a sublethal dose of Escherichia coli endotoxin. The results could be used in veterinary practice to identify similar symptoms in horses, predict the course of their development, and tailor a suitable treatment protocol.