A dressage girth is a short saddle girth used together with dressage saddles that have long girth straps. Since the straps reach far down the horse's side, a shorter girth is needed so it does not come too close to the elbows. A shorter girth also provides a cleaner contact between rider and horse, which is especially important in dressage. Common lengths for dressage girths are between 40 and 75 cm. Don't forget to regularly check the girth for wear, especially at the buckles!
