Anyone who has been present at a five-stage vetting of a prospective new horse may well have seen flexion tests being performed.
These will also be done during certain lameness examinations, for instance, if your horse is suspected to have degenerative joint disease, perhaps of the fetlock joint, then a flexion test will be one of the investigative tools the vet could use.
Each vet is an individual so each different vet will apply different amounts of force on each joint and may well vary the time he or she keeps the joint flexed. Remember though that each vet will be comparing like with like each time they conduct a test.
The joints are held flexed for a minimum of 30 seconds. As soon as the leg is released, the horse is trotted off from a standing position.
The vet is looking primarily at the first six strides or so to see whether a horse is showing lameness or not. If he does see lameness, further investigations would follow, as flexion tests do not pinpoint particular joints.