Evaluation of dimethyl sulphoxide effects on initial response to endotoxin in the horse

Reasons for performing study: Endotoxaemia is one of the most severe and ubiquitous disease processes in horses. Although dimethyl sulphoxide (DMSO) is used clinically in horses, there is no study indicating its efficacy in endotoxaemic horses. Hypothesis: DMSO ameliorates the clinical response to i.v. lipopolysaccharide (LPS) administration. Methods: Eighteen horses were assigned randomly to one of 4 groups: Normosol-LPS (0.2 μg/kg bwt, i.v.); DMSO (1 g/kg bwt, i.v.)-saline; high-dose DMSO (1 g/kg bwt, i.v.)-LPS; low-dose DMSO (20 mg/kg bwt, i.v.)-LPS. Horses participating in the DMSO-saline group were later assigned randomly to one of the LPS groups. Data for physical parameters, white blood cell counts, plasma TNF-?, and blood lactate and glucose concentrations were examined for the effect of treatment using a repeated-measures mixed-model ANOVA. A value of P<0.05 was considered significant. Results: Endotoxaemia occurred in all horses receiving LPS, as indicated by the clinical score, physical parameters, haemoconcentration and leucopenia. High-dose DMSO ameliorated the effect of LPS on fever. DMSO, at either dose, but did not have a significant effect on LPS-induced changes in all other evaluated parameters. Conclusions: In this study, DMSO had minimal effects on clinical signs of induced endotoxaemia in horses. The effects were manifested by amelioration of LPS-induced fever. Potential relevance: DMSO does not appear to have a significant protective effect against induced endotoxaemia; however, since some protective effect appears to exist further studies are needed in order to determine the role of DMSO in the treatment of endotoxaemia.