LAUSR

BACKGROUND In human medicine, local and regional arterial wall stiffness (AWS) parameters are routinely used to assess vascular health. In horses, information regarding reproducibility of ultrasonographically derived AWS parameters are lacking. OBJECTIVES To evaluate the inter-day and inter-observer and intra-observer measurement variability of both local and regional AWS parameters in horses. STUDY DESIGN Experimental study. METHODS In ten healthy, adult Warmblood horses, B-, M-mode and pulsed wave Doppler ultrasound images were collected on two different days from aorta, cranial and caudal common carotid artery and external iliac artery. Heart rate and non-invasive blood pressure were recorded simultaneously. From blinded data, diastolic and systolic vessel lumen areas and diameters were measured from B/M-mode images and the velocity of the pressure wave was determined by pulsed wave Doppler spectra. From each horse, one examination was measured again by the same observer and by a second, independent observer. Local and regional AWS parameters were calculated and inter-day and inter-observer and intra-observer measurement coefficients of variation (CV) were assessed. RESULTS Low CV were found for both arterial diameter and lumen area measurements. Moderate to high CV were found for local AWS parameters, while regional AWS parameters had low CV. MAIN LIMITATIONS The number of horses investigated was too low to obtain reference values. The inter-operator variability was not evaluated. CONCLUSIONS Our results show good reproducibility of aortic, carotid and external iliac artery diameter and area measurements using both B- and M-mode ultrasonography. Nevertheless, the variability of the derived local AWS parameters was relatively high. Therefore, local AWS parameters might be less suitable for follow-up studies, although they might be useful for population studies. On the other hand, regional AWS parameters showed low CV, making them valuable for both follow-up and population studies.