Advances in Diagnosing Equine Lameness

Advances in Diagnosing Equine Lameness

May 2011

By James E. Bryant, DVM, DACVS, Pilchuck’s Equine Department Head, Staff Surgeon and Lameness Specialist

Noticing a change in your horse’s gait is a worrisome experience. Because lameness can be caused by pain from just about any part of a horse’s body, proper treatment relies on accurately sourcing the problem. Fortunately, our understanding of lameness and the availability of new technologies to facilitate a diagnosis have increased significantly in the last 10 years.

Lameness exam: The first step toward a definitive diagnosis is a lameness exam. Because horses can’t tell us where it hurts, we must systematically determine the source of pain. When there is obvious swelling, heat and pain, the cause is usually easily identifiable. More commonly, there are no outside signs.

First, the veterinarian runs his or her hands over the horse to identify sources of heat, pain or swelling. Next, the horse is evaluated in hand, and the affected limb is identified. Flexion tests and trotting in circles are used to further localize the source of pain.

Next, diagnostic nerve blocks are used. We place local anesthetics over the nerves, starting from the bottom of the limb and working our way up until the pain has gone away. When the horse travels sound, we know the source of pain is between the last and current nerve blocks. Now, we move to diagnostic imaging for an accurate diagnosis, treatment plan and prognosis.

Diagnostic imaging: In simple terms, radiographs (X-rays) are used for evaluating bone, ultrasound for soft tissue structures, and magnetic resonance imaging (MRI) for either soft tissue or bone.

Digital radiology allows for rapid, on-site evaluation of arthritis, fractures, bone degeneration, OCD lesions, tendon or ligament attachment problems, and sites of soft tissue swelling or infection. Limitations include difficulty in reaching the hip or back, bone contusions (which cannot be seen with radiographs), and knowing the findings are clinically significant.

Ultrasound allows for good visualization of tendons, ligaments, joint capsules, cartilage and bone surfaces. While convenient (often portable and used stall-side), limitations include not being able to penetrate the hoof capsule or deep structures such as the pelvis, and lack of sensitivity for some deep structures (e.g., suspensory ligament).

MRI is the latest tool in our armamentarium and allows for visualization of bone and soft tissue like never before. We can accurately diagnose tears in the deep tendon in the foot, reassess our diagnosis of navicular disease, and look at collateral ligaments of the coffin joint, to cover just a few. With the MRI at Pilchuck, we can visualize any body part from the carpus (knee) in the front limb to the hock in the rear limb, along with the head and parts of the neck.

In summary, veterinarians are now able to more accurately pinpoint the pain causing lameness and treat more effectively – with a better outcome for you and your horse.

For more information, contact Pilchuck’s equine services department at 360.568.3111 or visit www.pilchuckvet.com.