Horses with a history of lameness, poor performance, or an apparent problem with a limb should have a lameness exam.
The lameness exam is a multi-step methodical veterinary exam wherein a veterinarian tries to determine which limb (or limbs) is lame and where specifically the pain in the limb originates. Only by finding the pain site and anatomy involved, and somehow alleviating the pain, can lameness be properly and directly treated. This is also the only way that a prognosis and management plan can be provided.
Generally, lameness exams consist of (1) a careful history, (2) a standing exam, (3) an exam in movement (mostly at the trot if possible) (4) flexion and hoof tester exams, (5) diagnostic anesthesia – nerve blocks, and (6) imaging the site of injury – radiographs, ultrasound, MRI and others. The diagnosis treatment plan and prognosis are derived from a synthesis of findings from all of the above parts of the lameness exam.
HISTORY: The first step in a lameness evaluation is a thorough history of both the horse and the owner/ traimer’s account of the problem. Information gathered about the horse includes breed, age, and prior use all of which provide clues to the problem. The history of the lameness includes the date that lameness was first noticed, how severe the lameness has been, and how it occurred, if known. All of these are important questions that we ask and you should try to be as complete as possible in your responses.
STANDING EXAM: A standing examination is done at a distance to evaluate the horse’s conformation and general appearance. This is followed by more careful examination and palpation of specific anatomic structures for swelling, heat, and pain. It also includes an assessment of body condition, posture, scars, and static flexion (manipulation of various structures in the standing horse for range of motion and pain response).
EXAM IN MOVEMENT: The next part of the exam involves watching the horse in movement. Lameness is mostly evaluated at the trot. Most thorough lameness exams are performed on firm to hard, consistent footing Examination often includes circles to both directions and may include inclines or specific patterns. For the diagnosis of some types of lameness problems, having a rider up can be advantageous.
FLEXION EXAMS AND OTHER MANIPULATIVE TESTING: Flexion exams involve putting specific joints or regions of the limb under stress for a specified and consistent period of time. The horse’s degree of lameness is assessed before and after flexion. The result, which is the change in severity of lameness following flexion, provides additional information regarding the origin of the pain. As with many parts of the exam, flexion tests must be interpreted in light of what is normal for that specific horse. Wedge tests, extension tests are similar in principle. The specific ones used depend greatly on the practitioner’s preference and experience.
HOOF TESTERS: Hoof testing involves the use of a pincer-like tool to put pressure on specific regions of the foot in search of a pain response. As with flexion exams, the key to accurate interpretation of hoof tester examination is knowledge of what constitutes a normal response. This can only be gained through a methodical approach, and lots of experience with different types of horses and hooves.
At this point in the exam, the veterinarian usually has determined which limb is lame, and may have an idea where the pain is located within that limb. Often, nerve blocks may then be necessary to determine precisely where the pain is located.
NERVE & JOINT BLOCKS: Nerve blocks are used to methodically numb portions of the limb as a means of finding the site of pain, using the process of elimination. Also known as diagnostic anesthesia, “blocking” is the injection of a local anesthetic agent around specific nerves or into specific joints or other structures. The horse is examined at the trot before the block, and the degree of lameness determined. Then the area in question is numbed, and the horse is asked again to trot off. Either there is improvement in the lameness or not.
If there is not, the process is continued on specific nerves progressing up the limb until the lameness is visibly lessened. Specific joints and tendon sheaths can also be blocked for a more specific localization of lameness. Blocks into a joint or tendon sheath require surgical cleanliness to prevent infection of these structures. Limitations include spread of local anesthetics to adjacent regions, clouding the interpretation of the result.
IMAGING THE SITE OF PAIN: Once the site of pain is located, diagnostic imaging is used to view the structures in the area and provides additional information about the nature of the injury. This most commonly includes radiographs (x-rays) to image bone, followed by ultrasound to image soft tissues. Cases not fully understood using these diagnostics may require the use of MRI, CT Scan or Nuclear Scintigraphy (bone scan), among others to provide more detailed information.
The lameness exam is the cornerstone of the equine practitioner’s art. Many of us have developed and perfected this exam through our veterinary careers. It is as much an art as science. It relies to a great extent on our knowledge of anatomy, pattern recognition, meticulous technique, horsemanship, knowledge of the horse type and discipline, and the ability to tie all aspects of clinical assessment together with other diagnostics and imaging.
See the related Topic: “Subtle or Hard to Diagnose Lameness: What Horse Owner’s Should Know” for a more detailed discussion of these advanced diagnostics.
Reasons to UseRelated Observations
The lameness exam is the hub of diagnostics for lameness and performance problems. The results of a lameness exam provides direction for further diagnostics and treatment.
Even the most experienced and talented lameness clinicians run into problems that are very difficult to diagnose, especially in the hind limbs. The lameness exam may point to an anatomic location, but require other diagnostics (imaging) to determine the nature of the condition.
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