EN
The studies aimed to induce endotoxin tolerance in horses and to evaluate this state with regard to clinical observations. Investigations involved 8 clinically healthy mares subjected to 4 iv. injections with 0.1 μg/kg b.w. doses of LPS from E. coli each; the three fast doses (LPS-1, LPS-2, and LPS-3) were given daily whereas the fourth injection (LPS-4) was performed one week after LPS-3. Rectal temperature, heart and respiratory rates were measured before LPS administration and 1 h, 2 h, 3 h, 5 h, and 7 h thereafter. The first dose of endotoxin produced a rise in body temperature by 0.8°C after 2 h. However, the consecutive injections weakened temperature response which indicated stimulation of an early-type pyrogenic tolerance. Statistically significant differences between the LPS-1 and LPS-2 responses were found 1 h and 2 h after injection. The administration of LPS-4 produced less visible body temperature alterations suggesting tolerance attenuation after 7 days. Mean respiratory and heart rates were the highest after LPS-1 but no significant differences after subsequent injections were found.