At ten or twelve the look and body are still there,and the head piece never coarsens. Very often they will be at the top of the chart or even a little over through early growth stages, so you will use the weight to gage the final outcome. The first type tends to produce more moderately. Different Sheltie lines do follow different growth patterns, so if anyone has information on growth rates for other specific lines, I'll post them too. Note also that with any chart it is wise to look at how fast the dog is growing relative to the rate shown on the chart as well as how tall the dog is.
Size is measured at the highest point of the shoulder blades, just behind the base of the neck.
The dog should be measured standing on a hard, level surface with the front legs vertical and the head in a natural position. Stand the dog with its front feet lined up with the yardstick and slide the triangle or rectangle down until it just rests on the withers. Read the dog's height from the yardstick at the bottom edge of the cardboard. Some historical perspective on the size problem might be in order. A register shall be kept of members' dogs 12 to 15 inches.