Clinical Exam of the Lame Horse: Life Without MRI

Take Home Message—The equine practitioner must undergo a specific type of examination to evaluate a horse’s musculoskeletal system, including observation and palpation when the horse is at rest or in motion. This type of exam can be done as the horse exercises in his field of work or competition. In a world where we have more technology available (such as MRI) for our medical imaging, practitioners need to be more accurate in their clinical skills. This paper will discuss different tests to see what they can offer to the practitioner in order to get as deep as possible into a diagnosis before picking up an imaging technology.

I. Introduction

The equine practitioner has become more specialized in their work as clients ask for more detailed examinations, with lameness exam being the most requested. The practitioner should have a good knowledge of major sources of discomfort, as well as anatomy, joint and tendon biomechanics. An understanding of foot lameness and farriery is important as these are the most common problems in the lame horse. Horses are examined at rest and in motion, evaluated conventionally in hand or under tack, during harder exercise or when they are competing.

II. Principles of the orthopaedic exam

Horse should be evaluated with a series of observations and tests in order to identify a source of gait abnormality or lameness.

Exams at Rest

Auscultation

Since orthopaedics is normally a part of a full clinical exam, the author recommends auscultation of the heart and lungs. The main purpose is to avoid missing a serious disorder that may not allow a sport horse to achieve its goal. For example, if the horse has atrial fibrillation, then orthopaedic issues might become of less interest.

Observation

This exam is done in a quiet place with the horse placed in a stall or on a cross tie and allows the practitioner to go around and observe the horse visually before palpation is started.

The veterinarian should observe the behaviour and vigilance of the horse and the way the horse stands. For example, is the horse non-weight-bearing a hind limb with potential lumbar pain, or putting one fore limb forward or in light adduction to release heel pain or medial heel pain. The overall conformation should be observed for abnormal amyotrophy as well as any asymmetry of limbs or asymmetry of the muscling of neck and top line. The horse should also be observed for asymmetric weight bearing, shoeing and front feet abnormalities such as toe in or out, or feet asymmetry giving history of abnormal overload on wider foot. Hind limbs and front limbs should be observed for major deformities such as conformation such as a long pastern and low fetlock position enhances suspensory strain.

Palpation

A tip of the nose to tip of the tail evaluation is made including teeth, jaws, base of the skull, neck withers, back and hind quarters. There is a need to evaluate each main joint from top to bottom with mostly the thumb and index finger to evaluate each synovial recess. On sport horses, time is spent on stifles, hocks, front and hind fetlocks and front coffin joints. Soft tissues, including muscles, tendons (especially flexor palmar and plantar), and collateral ligaments can be easily assessed looking for heat, deformity or pain to pressure.
 

Passive Tests

A series of slow motion tests can be done on the body of the horse and include the following:

• Passive flexion tests of the joints (fetlocks and coffin joints, or hocks and stifles)
• Passive protraction and retraction of the proximal joints of the limbs
• Passive tests of the neck and the back assessing latero-motion and extension/flexion

For these three types of tests, the key is the range of motion (ROM) and potential pain at the end of flexion or extension. For example, a fetlock joint flexion may show pain as the flexion is at its higher range of flexion with a dorsal capsulitis.

• Hoof tests of both front feet (or hinds if necessary)

Hoof testing is not always documented but can allow the practitioner to target an area of pain on the sole or wall of the foot. There are different receptors in the foot which can indicate potential deep or superficial pain in relation to the pressure and time of pressure on the affected hoof. The board extension test on the front feet elevates the toe and creates a strain in the palmar part of the foot. This test is positive when the horse tries to jump from the board or extend the whole body backwards. If it is positive, pain is indicated in the deep flexor tendon and insertions, the navicular bone, the palmar coffin joint and capsule, and sometimes the collateral ligaments. These abnormal findings are reported on a grid or on a paper in order to coordinate any further assessment.

An entire chapter in this presentation could be devoted to neck and back pain. It’s amazing to see how many horses change and adapt their axial skeleton towards even minor distal limb issues. This explains part of the success of chiropractors or osteopaths, whose evaluation of the top line has been more thorough and detailed, thus picking up abnormal tension as a consequence of a distal limb problem.

The exam of the back and neck are done with one hand on each side to palpate and feel any muscle tension, heat or abnormal spasm. This is repeated after the horse is worked because it is of interest to re-evaluate these structures once the horse has been warmed up. Some may disappear, signifying a more superficial issue. Some of them will be consistent or worse after exercise, and might be related to more significant problems involving deeper structures, either bone, muscles, ligaments or joints.  [...]