Clinical and immunomodulating effects of ketamine in horses with experimental endotoxemia.

The research examines the effect of ketamine on the immune response of horses subjected to experimental endotoxemia, with results showing that the administration of subanesthetic ketamine was well-tolerated but did not significantly influence the clinical or immunologic response.

Objective and Methods

• The central aim of this study was to determine if subanesthetic doses of ketamine can mitigate the clinical and immunologic reactions to experimental endotoxemia in horses.
• The researchers conducted an experimental study involving nineteen healthy mares of varying breeds.
• The horses were randomly divided into two groups: a group treated with ketamine (KET) and a group treated with saline (SAL).
• Each group was subjected to a dosage of lipopolysaccharide (LPS), a bacterial endotoxin, one hour after a continuous rate infusion (CRI) of either ketamine or saline.
• The clinical and hematological responses were documented, including plasma concentrations of inflammation markers – tumor necrosis factor-α (TNF-α) and thromboxane B(2) (TXB(2)).

Results

• All the horses included in the study completed the experiment safely.
• The ketamine-treated group displayed temporary excitement during the ketamine loading infusion and an hour after its discontinuation. This reaction was statistically significant when compared to the saline-treated group.
• An increase in neutrophilic leukocytes, a type of white blood cell, was detected in the ketamine-treated group eight and twenty-four hours after endotoxin administration. This change was also significant compared to the saline group.
• Minor abnormalities in plasma biochemistry were considered clinically insignificant.
• Both groups showed a peak in TNF-α and TXB(2) production 1.5 and 1 hours respectively, post endotoxin administration. However, the difference in production between the ketamine and saline groups was not statistically significant.

Conclusions

• The administration of subanesthetic ketamine through a CRI was well received by horses.
• Despite initial hypothesis, the study didn’t identify a significant impact on the clinical or immune response to the endotoxin administration in healthy horses when treated with a subanesthetic dosage of racemic ketamine.