title: Clinical and immunomodulating effects of ketamine in horses with experimental endotoxemia.
abstract: BACKGROUND
  Ketamine has immunomodulating effects both in vitro and in vivo during experimental endotoxemia in humans, rodents, and dogs.
  
  
  OBJECTIVE
  Subanesthetic doses of ketamine will attenuate the clinical and immunologic responses to experimental endotoxemia in horses.
  
  
  METHODS
  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 B(2) (TXB(2)) 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 TXB(2) 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
  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 TXB(2) production, was not identified in healthy horses with the subanesthetic dose of racemic ketamine utilized in this study.
authors: Lloyd Veterinary Medical Center, College of Veterinary Medicine, Iowa State University, Ames, IA 50011-1250, USA. cjalcott@iastate.edu
authors: C J
authors: CJ
authors: Alcott
authors: B A
authors: BA
authors: Sponseller
authors: D M
authors: DM
authors: Wong
authors: J L
authors: JL
authors: Davis
authors: A M
authors: AM
authors: Soliman
authors: C
authors: C
authors: Wang
authors: W
authors: W
authors: Hsu
mesh_terms: D000818:Animals; D019540:Area Under Curve; D001831:Body Temperature / Q000187:drug effects; D019446:Endotoxemia / Q000188:drug therapy / Q000276:immunology / Q000662:veterinary*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006734:Horse Diseases / Q000188:drug therapy* / Q000276:immunology; D006736:Horses; D007155:Immunologic Factors / Q000008:administration & dosage*; D007649:Ketamine / Q000008:administration & dosage*; D008070:Lipopolysaccharides / Q000008:administration & dosage; D011897:Random Allocation; D012119:Respiration / Q000187:drug effects; D018709:Statistics, Nonparametric; D013929:Thromboxane B2 / Q000097:blood / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000276:immunology
chemical_list: D007155:Immunologic Factors; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D013929:Thromboxane B2; D007649:Ketamine