Equine endotoxemia: cardiovascular, eicosanoid, hematologic, blood chemical, and plasma enzyme alterations.

This research article investigates the effects of chronic sublethal endotoxin, using Escherichia coli lipopolysaccharide (LPS), on cardiac output and other indicators in ponies, as well as the potential protective effects of the medication flunixin meglumine.

Research Design and Methodology

• The study used ponies fitted with electromagnetic blood flow transducers around their pulmonary and coronary arteries. Two groups of ponies were administered with progressively increasing doses of LPS over 24 hours.
• Group 1 represented the control group and was not treated with any medication. Group 2, on the other hand, was pre-treated with Flunixin Meglumine before each LPS dose.
• The researchers measured several parameters including cardiac output (CO), stroke volume, left coronary blood flow (LCBF), plasma thromboxane (TX; as indicated by TXB2), prostacyclin (indicated by 6-keto-prostaglandin PGF1 alpha), and hematologic and blood chemical values.

Key Findings

• The initial LPS inoculation in the untreated ponies (group 1) led to significant increases in TXB2 and 6-keto-PGF1 alpha values. These values returned to baseline six hours after each LPS administration.
• Interestingly, repeated exposure to LPS resulted in high plasma concentrations of 6-keto-PGF1 alpha, yet the TXB2 production became less with each successive LPS administration. This suggests that the initial inflammatory response to endotoxin exposure might gradually diminish over time.
• In conjunction with increased 6-keto-PGF1 alpha values, cardiac output decreased to around 55%-60% of baseline values. Left coronary blood flow could not be accurately evaluated however.
• Severe lactic acidosis developed in the ponies from group 1, implying the onset of life-threatening physiological changes due to endotoxemia.
• Contrarily, group 2 ponies remained clinically normal. This indicated that flunixin meglumine provided protection to the cardiovascular system and peripheral perfusion during endotoxemia. Hence, this drug might be beneficial in maintaining cardiovascular function and tissue perfusion during instances of endotoxemia.
• It was also observed that Flunixin meglumine doesn’t affect the cardiovascular function in healthy ponies, implying its safety profile.

Abstract Summary

• The study explores the detrimental effects of chronic sublethal endotoxin exposure, specifically on cardiac output and inflammation parameters, and the possible protective role of flunixin meglumine.
• The results demonstrate the potential use of flunixin meglumine to protect against the harmful physiological changes brought on by endotoxemia in ponies.