Sizing Guideline
To choose the right size, it is necessary to measure the circumference of the front cannon bone. Take a tape measure and wrap it around the middle of the cannon bone without tightening too much to take the measurement.
Circumference of Front Cannon Bone
Small 17 cm - 20 cm (6.5 to 9 inches)
Medium20 cm - 23 cm (9 to 10 inches)
Large Over 23 cm (over 10 inches)
If you are buying protection for the hind legs, the measurement is normally taken on the front limb. It is in fact very uncommon that between front and rear legs, there is such a difference to require boots of different sizes.