Clinical, Hematological, and Biochemical Analysis of Experimental Endotoxemia in Thoroughbred Horses

Abstract

To evaluate the biological response of the horse to endotoxemia, a sublethal amount of lipopolysaccharide (LPS) (10 μg/kg) was given to two Thoroughbreds in two doses 24 hr apart. Each infusion initially produced a significant increase or decrease in rectal temperature, an increase in respiratory rate and heart rate, and a marked decrease in white blood cell count (WBC). The horses subsequently showed signs of shock, characterized by extreme coldness of the skin of lower limbs, as well as cyanosis of the visible mucosae, oliguria accompanied by proteinuria, and abnormalities in gastrointestinal function. The clinical signs of equine endotoxemia may be manifested by the clinical condition of the systemic inflammatory response syndrome (SIRS): two or more of the above signs, such as high or low rectal temperature, increased heart rate and respiratory rate, and leukopenia. Pathobiological responses such as a severe decrease in the number of platelets, hypoglycemia, metabolic acidosis, disorders of hemostasis accompanied by cyanosis of the visible mucosal membranes, proteinuria and oliguria, and abnormal gastrointestinal function, may be manifestations of pathobiological conditions ranging from disseminated intravascular coagulation (DIC) to multiple organ dysfunction syndrome (MODS). Therefore, the clinicopathological responses in equine endotoxemia suggest the nature of SIRS elicited by hypercytokinemia progressing into septic shock.