Our previous study suggested that measurement of the unit area sweating rate (SR) at the neck in horses was suitable for estimation of the total sweating rate of a horse during exercise. We developed a special garment made of high-absorption polymer sheets to be fitted on the horses for measuring the total SR, and examined the relationship between the unit area SR at the neck and the total SR in a horse. The correlation between the total SR and the unit area SR at the neck was found to be highly significant (r=0.9254, P<0.01). Total sweating rate (kg) = 0.2676 X (unit area sweating rate at the neck (g)) + 0.6735 (r² = 0.8563 P<0.01). We considered that the total SR could be calculated from the unit area SR at the neck based on the results of our previous study, and derived the aforementioned formula.

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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.

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Plasma K accumulation during exercise results from the balance between exchange through biological membranes (mainly muscle fibres and erythrocytes), distribution to other tissues and the haemoconcentration. In the present study, the effect of exercise and training on plasma K concentrations and its relationships with other physiological variables have been analysed in two equine breeds. Twenty male Andalusian (AN) and ten Angloarabian (AA) horses, 7 females and 3 males, were subjected to two standardised exercise tests, composed of four workloads, before and after training. Heart rate (HR) was monitored and venous blood was withdrawn at rest, before each exercise level and during recovery. The following parameters were analysed: packed cell volume (PCV), plasma K, lactate (LA) and total protein (TPP). Furthermore, the horses were filmed and three kinematic parameters were studied: stride duration (SD), frequency (SF) and length (SL). Exercise induced an increase in K from 6 and 8 m/sec in AA and AN horses respectively, a steady-state until the end of the exercise and a decrease after 2 min of recuperation. Some interbreed differences existed, with higher K levels in the AN horses, due to the higher relative exercise intensity, stride frequency and haemoconcentration. K was correlated with HR, PCV, TPP, SL, SD and SF. Training caused a decrease in K in AN, but not in AA horses. Plasma K seems to be a good indicator of the physical effort intensity, fitness and training degrees, but it was not related to the magnitude of the glycolytic response to exercise.

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