Lameness comes in two basic forms: primary and secondary. Primary asymmetry occurs as a consequence of an event that originates independent of other preexisting lameness. Trauma, breed, age, and poor conformation could all play a role in the development of primary lameness. Identifying the primary gait deficit(s) is the chief goal of the veterinary examiner, because this is where treatment will eventually be directed.

Secondary lameness, on the other hand, manifests as a consequence of one or more preexisting gait deficits elsewhere in the horse. It can be genuine (as in cases of associated and compensatory issues) or artificial (as in the case of referred asymmetry).

The relationship between primary and secondary lameness is unidirectional (fig. 7.1). Secondary lameness would not exist without the presence of a primary underlying problem. This is an important concept when considering the fact that permanent resolution of secondary lameness would, at least in part, demand mitigation of its primary counterpart. As long as a primary problem exists, the potential for secondary pathology is not far behind.