Intra- and interobserver variability of ultrasonographic measurements of the thyroid gland in healthy beagles

The repeatability of ultrasonographic measurements of the canine thyroid gland was evaluated. The variability of three different parameters (the maximal length, width, and height) within observer, between observer and between dogs was assessed based on three different measurements made by each of three observers in five healthy beagle dogs. From the three parameters, the volume of the gland was estimated using a formula of a rotation ellipse. The height and the volume had the lowest intra- and interobserver variability, while measurements of the length had the biggest intra- and interobserver variability. The mean values, with their 90% confidence interval were: height = 0.53 cm [0.33-0.73], length = 2.45 cm [2.04-2.85], width = 0.62 cm [0.460.78], volume = 0.38 cm(3) [0.20-0.55].