In the present study, the HDO device gave higher values in systole com pared to the Cardell device. This could partly be related to the difference in cuff size between the two devices. The size of the cuff is known to influence the obtained blood pressure values where a cuff that is too wide underesti mates the blood pressure whereas a cuff that is too narrow tends to overestimate the values. The optimum cuff width for horses is one fifth of the tail circumference. It is therefore important that the cuff used is adjusted for each type of horse and the greater cuff size of the Cardell might be preferable in horses with a wide tail, such as some of the Icelandic horses in the present study. However, the results from the present study indicate that both devices can be used to measure systemic blood pressure in Stand ardbred as well as Icelandic horses.

There are results that indicate that the HDO device has a better correlation with the direct blood pressure measurement technique com pared to the Cardell device. A previous study in dogs also showed that although the blood pressure values obtained with the HDO device showed a greater variability than the values obtained with the direct blood pressure measurement technique, there was a good correlation be tween the two techniques. Both devices can be run on battery, which makes it possible to use them during field conditions. The results from this study showed that the Cardell device had less interday variation in systole compared to the HDO device.

However, the Cardell is large and impractical to handle in a field setting whereas the HDO device is smaller in size, lighter Drug_discovery and easier to handle. The previously reported high sensitivity and good correlation with the direct blood pressure measurement technique for the HDO device is also advantageous. Conclusions In conclusion, indirect blood pressure measurements, plasma ET 1 and serum cortisol all showed an acceptable interday variation and are candidates for further investiga tion in horses with Equine metabolic syndrome. Both the Cardell and the HDO device can be used for measurement of indirect blood pressure in horses, but the HDO was most practical to handle, especially in a field setting. There seem to exist a breed difference in the concentrations of plasma ET 1 and serum cortisol. Transportation and housing in a new environment seemed to influence the concentrations of plasma ET 1 but not serum cortisol. All of these factors need to be considered when indirect blood pressure, plasma ET 1 and serum cortisol are used in a clinical set ting. Future studies that investigate the possible seasonal variation in blood pressure, ET 1 and cortisol on healthy horses of different breeds and of horses clinically affected of EMS are desirable.