Contact on the inside of the diagonal fore and hind feet is referred to as what?

The correct answer is that contact on the inside of the diagonal fore and hind feet is referred to as cross-firing. This term specifically addresses the action where the hoof of the hind leg contacts the hoof of the front leg on the same side, which can cause uneven wear or injury to the horse's legs. Cross-firing usually occurs when a horse is moving at speed, such as during a canter or gallop, and can be indicative of improper gait mechanics. Understanding this term is important for horse evaluation, as it can affect the horse's performance and overall soundness.

The other terms mentioned, such as scaling, forging, and displacement, pertain to different issues or conditions. Scaling generally refers to the condition of the hoof wall, often due to improper care or environment. Forging, on the other hand, is a situation where a horse's hind foot strikes the front foot, which is distinct from cross-firing in that it does not involve the diagonal nature of the footfall. Displacement typically relates to an abnormal movement or position of a limb or joint rather than the interaction of hooves during movement. Understanding these distinctions helps in accurately assessing and addressing the physical behaviors of horses during evaluation.