Endotoxin-induced digital vasoconstriction in horses: associated changes in plasma concentrations of vasoconstrictor mediators
Article first published online: 5 JAN 2010
2004 EVJ Ltd
Equine Veterinary Journal
Volume 36, Issue 3, pages 273–278, April 2004
How to Cite
Menzies-Gow, N. J., Bailey, S. R., Katz, L. M., Marr, C. M. and Elliott, J. (2004), Endotoxin-induced digital vasoconstriction in horses: associated changes in plasma concentrations of vasoconstrictor mediators. Equine Veterinary Journal, 36: 273–278. doi: 10.2746/0425164044877260
- Issue published online: 5 JAN 2010
- Article first published online: 5 JAN 2010
- Paper received for publication 22.09.03; Accepted 22.01.04
Reasons for performing study: Lipopolysaccharide (LPS) infusion reduces digital perfusion, but the mediators responsible remain undetermined.
Objectives: To identify vasoconstrictor mediators released following LPS infusion and relate their appearance in plasma to digital blood flow alterations.
Methods: Blood flow in the lateral digital vessels of 6 Thoroughbred horses, following a 30 min infusion of LPS (E. coli 055:B5; 30 ng/kg), was measured using Doppler ultrasonography. Concomitant measurements of hoof wall and coronary band surface temperatures (HWST and CBST) were made. Serial blood samples were collected and plasma LPS, tumour necrosis factor α (TNFα), 5-HT, thromboxane B2 (TxB2) and endothelin measured.
Results: Plasma LPS concentrations reached a maximum of 13.2 pg/ml during the infusion, followed by an increase in plasma TNFα concentration. Digital arterial and venous blood flow decreased by 43 and 63%, respectively; HWST and CBST similarly decreased. Systemic blood pressure remained unaltered. Plasma concentrations of TxB2 and 5-HT increased, coinciding with the onset of digital hypoperfusion. Plasma endothelin concentrations remained unchanged.
Conclusions: The temporal relationship between the onset of digital hypoperfusion and increases in plasma 5-HT and TxB2 concentrations is consistent with these platelet-derived mediators being associated with LPS-induced laminitis.
Potential relevance: These experimental data support the use of anti-platelet therapy in the prevention of laminitis associated with endotoxaemic conditions.