A "joint block" involves the sterile injection of a temporary local anesthetic into a joint during a lameness exam. This procedure is very important for determining whether or not a specific joint is the location of the condition causing the lameness. Unlike a nerve block, which anesthetizes a region, a joint block is more specific.

In this procedure, the hair over a joint many or may not be clipped. The skin is disinfected (scrubbed) surgically to prevent bacterial infection when a needle is placed through the skin and into the joint. Sterile gloves are used. The same process takes place in blocking of other synovial structures, such as tendon sheaths and bursae. Once the local anesthetic has been injected into the joint, a precise time for effect is allowed. At that point, the horse is reexamined to see if lameness is improved.