Effects of polymyxin B and Salmonella typhimurium antiserum on horses given endotoxin intravenously.

The research tested the potential protective effects of polymyxin B and an antiserum against Salmonella typhimurium in horses injected with endotoxin, a harmful substance. The results suggested that polymyxin B may be beneficial in treating endotoxemia in horses, while the antiserum showed no positive effect and may even make the endotoxin effects worse under certain conditions.

Research Methodology

• This study utilized a sample of six foals aged between three to five months to evaluate the potential protective effects of polymyxin B and Salmonella typhimurium antiserum against injected endotoxins.
• The researchers administrated endotoxins into the foals intravenously, at a dosage of 0.25 micrograms per kilogram of body weight, either without any pretreatment or preceded by pretreatment with either polymyxin B at a dose of 6000 units per kilogram, or Salmonella typhimurium antiserum at a dose of 1.5 milliliters per kilogram.

Findings

• Endotoxins administration without pretreatment resulted in transient recumbency, increased rectal temperature, and accelerated heart and respiratory rates. It also led to leukopenia and a rise in tumor necrosis factor (TNF) and interleukin 6 (IL-6).
• Pre-treatment with polymyxin B resulted in significantly lower increases in plasma TNF and IL-6 activities, rectal temperature, and respiratory rate compared to when endotoxin was administered alone.
• Use of the Salmonella typhimurium antiserum, on the other hand, resulted in a significant increase in the respiratory rate, maximal plasma IL-6 activity, and total TNF response compared to when endotoxin was given without pretreatment.

Conclusions

• Polymyxin B shows promise as a potential treatment for endotoxemia in horses, due to it substantially alleviating the adverse effects of endotoxin.
• In contrast, the Salmonella typhimurium antiserum was found to not only have no positive effects on mitigating the impact of endotoxin but may also exacerbate the endotoxin’s detrimental effects under certain conditions.