Horsewalkers - should they be round or oval?

 Horsewalkers are used extensively in the management and training of horses. They permit controlled exercise of horses at walk and trot and are less labour intensive than most other forms of controlled exercise, such as walking in-hand, lunging, riding, swimming or running horses on treadmills.

Dr David Marlin & Paul Farrington (European Trainer - issue 18 - Summer 2007)