How do you fix a horse that is cinchy or girthy and shows aggression or pain when saddled?

A cinchy or girthy horse — one that pins ears, snaps, kicks, or sucks in its belly when the girth is tightened — is a horse in which the girthing process has become associated with pain, discomfort, or anticipatory anxiety. Clinton Anderson is specific that this behavior must first be assessed for physical causes before training approaches are applied. Physical causes of cinchiness are common and include: ulcers — the pressure of the girth tightening against a horse with gastric ulcers can cause genuine pain and is extremely common in performance horses; saddle fit issues where the gullet or tree is pinching at the point of shoulder when the girth is snugged; girth galls or skin sensitivity from poorly fitted or maintained girth materials; and rib or thoracic vertebrae soreness. Anderson recommends veterinary evaluation specifically for ulcers before assuming cinchiness is behavioral, because the incidence of ulcers in performance horses is high enough that it should be on the differential diagnosis for any cinchy horse. If physical causes are ruled out, Anderson addresses cinchiness as a conditioned response — the horse has associated girthing with discomfort and now reacts to the approach of the girth regardless of whether current discomfort exists. His desensitization sequence involves rubbing the girth along the horse's belly repeatedly without tightening it, then applying it without tightening, then tightening minimally and walking before tightening more, building the horse's positive associations with girthing through many non-painful repetitions. Patience is required because cinchiness that has developed over years will not resolve in one session. Anderson teaches girthing two holes, walking, two more holes, walking, and completing the process incrementally every time until the horse's response to girthing normalizes.