Good conformation and inherent soundness are major prerequisites in the performance horse (Holmstrom & Drevemo, 1997). One of the most common conformational faults associated with the equine forelimb is splint formation. Particularly in the case of young horses (<5 years old), the formation of splints along the medial and lateral aspects of the cannon bone (3rd metacarpal) is often a cause of lameness. The splint bones are the smaller 2nd (inner or medial) and 4th (outer or lateral) metacarpal bones that rest along-side the cannon bone and the inner splint bone tends to be more frequently affected. Several conditions/activities such as inappropriate nutrition, hard ground, direct trauma as in the opposing hoof hitting the inside splint bone of the opposite leg and poor conformation (off-set knees) create an increased risk of splint formation. Pasture management is an important feature of horse production and growing horses spend much of the year at grass. While at pasture, overly excessive play and motor activity (slipping, falling and jumping) might also induce splint formation and lameness. Splints generally result from inflammation of the ligament that knits the splint and cannon bones together leading to inflammation of the periosteum (periostitis) and new bone formation at the damage site. In cases where substantial blunt trauma occurs, it may also involve the cannon bone and the occurrence of single or multiple swellings. Newly formed splints can cause degrees of lameness of the affected limb, but rest is usually sufficient to overcome the damage. The objective of this study was to compare two different grassland husbandry systems for rearing young sport horses with regard to the prevention of occasional lameness and splint formation in the yearling while at summer pasture.