What term describes a change in a horse's gait due to a response to pain?

Lameness refers specifically to a change in a horse's gait that occurs as a response to discomfort or pain, particularly in the legs or feet. This can be due to various underlying causes, such as injury, infection, or illness, leading the horse to exhibit an altered movement pattern as a way to minimize pain. The presence of lameness is typically indicated by signs such as limping, reluctance to move, or changes in the horse's stride or walking behavior.

In contrast, the other terms do not relate to gait changes due to pain. Colic describes abdominal pain and can manifest in various ways but is not specifically tied to gait alterations. Thrush is a bacterial infection affecting a horse's hoof and leads to foot problems but doesn't directly denote a change in gait. Rain rot is a skin condition caused by a bacterial infection, which also does not have a direct correlation to the horse’s gait. Therefore, lameness is the precise term that encapsulates the phenomenon of gait alteration resulting from pain.