Campus Units

Veterinary Diagnostic and Production Animal Medicine, Biomedical Sciences, Statistics

Document Type


Publication Version

Published Version

Publication Date


Journal or Book Title

Journal of Veterinary Internal Medicine





First Page


Last Page





Background:  Ketamine has immunomodulating effects both in vitro and in vivo during experimental endotoxemia in humans, rodents, and dogs.

Hypothesis:  Subanesthetic doses of ketamine will attenuate the clinical and immunologic responses to experimental endotoxemia in horses.

Animals:  Nineteen healthy mares of various breeds.

Methods:  Experimental study. Horses were randomized into 2 groups: ketamine-treated horses (KET; n = 9) and saline-treated horses (SAL; n = 10). Both groups received 30 ng/kg of lipopolysaccharide (LPS, Escherichia coli, O55:B5) 1 hour after the start of a continuous rate infusion (CRI) of racemic ketamine (KET) or physiologic saline (SAL). Clinical and hematological responses were documented and plasma concentrations of tumor necrosis factor-α (TNF-α) and thromboxane B2 (TXB2) were quantified.

Results:  All horses safely completed the study. The KET group exhibited transient excitation during the ketamine loading infusion (P < .05) and 1 hour after discontinuation of administration (P < .05). Neutrophilic leukocytosis was greater in the KET group 8 and 24 hours after administration of LPS (P < .05). Minor perturbations of plasma biochemistry results were considered clinically insignificant. Plasma TNF-α and TXB2 production peaked 1.5 and 1 hours, respectively, after administration of LPS in both groups, but a significant difference between treatment groups was not demonstrated.

Conclusions and Clinical Importance:  A subanesthetic ketamine CRI is well tolerated by horses. A significant effect on the clinical or immunologic response to LPS administration, as assessed by clinical observation, hematological parameters, and TNF-α and TXB2production, was not identified in healthy horses with the subanesthetic dose of racemic ketamine utilized in this study.


This article is from Journal of Veterinary Internal Medicine 25 (2011); 934: doi: 10.1111/j.1939-1676.2011.0749.x. Posted with permission.


Journal of Veterinary Internal Medicine articles are published under the terms of the Creative Commons Attribution Non-Commercial License (CC BY NC), which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Copyright Owner

American College of Veterinary Internal Medicine



File Format