Base narrow is a conformation in which the horse stands closer at the hooves or ground than at the origin of the legs at the chest. This is typical of heavy-muscled horses.
The base-narrow horse will travel with its hooves close in front and will land on the lateral side (outside) of the hoof wall. Due to extra weight placed on the outside of the hoof, horses develop conditions such as ringbone, sidebone, and heel bruising.
Horses with this conformational fault can be toed-in or toed-out.
For more information, see Relating Form to Function: Horse's Frontlegs, Front View.
