David Schwinghamer, DVM

October 2005

There are multiple aspects to determining equine lameness, and each of these aspects has its own challenges.  When evaluating lameness, it is best understood by taking a scientific approach.  Veterinarians start by viewing the “big picture” and by process of elimination start to fine tune the problem until a final diagnosis can be made.

WHEN DID THE PAIN BEGIN?

The lameness evaluation starts with a thorough history of the horse’s health and activities.  This helps your veterinarian rule out different types of lameness.  For example, a barrel horse that comes up suddenly lame after the turn at the second barrel probably doesn’t have laminitis.  It is important to try and remember all of the details of when your horse was last sound, when the lameness was first observed, and if the horse has improved or has become more lame.   

WHERE IS THE PAIN LOCATED?

The exam then progresses to determining which limb is affected and to what degree.  Pinpointing the correct leg can be difficult.  To help you try and determine this, there are a couple of tips to follow.  First, lameness can often be accompanied by heat and swelling.  Second, horses tend to nod their heads down on the sound limb and up on the affected limb if it is a fore leg lameness.  And lastly, hind limb lamenesses tend to present themselves with a shortening of stride and a hike in the hip of the affected leg.  Once the affected limb is identified, the next step is to identify the specific location on the limb that the lameness is coming from. 

Many tools and tests have been developed to help pinpoint lameness. They all focus on getting the horse to either show response to pain or to eliminate pain.  One tool is the hoof tester.  This tool applies pressure to the sole and frog of the foot in an attempt to find a sensitive spot that may explain the lameness.  Palpating the limb is one of the most useful tests used to examine the affected limb.  Palpation consists of feeling all the structures of the limb, especially the tendons, ligaments, and bone.  First, the joints are flexed and extended to check for proper range of motion, and then they are examined for effusion (swelling) or pain.  A flexion test can also be useful in determining joint pain.  The theory behind this exam is to stress or strain the joint by flexing it for approximately 60 seconds, and then to trot the horse off immediately.  Horses with pain in the flexed joint will show a significant increase in lameness.  Your veterinarian will first perform the appropriate tests mentioned above, and then once the lameness is isolated, use nerve block tests to help confirm that the pain is truly coming from the suspected area.  Nerve blocks are one of the most helpful tools used to help determine lameness.  The principle behind these tests is that a local anesthetic will numb the nerve at the sight of application, and everything down the leg from this spot lacks sensation and also pain.  When the pain is gone, the lameness should also be gone.

WHAT IS CAUSING THE PAIN?

Once the final location of the lameness is determined, the question then becomes “What is the cause of this pain?”  There are many different conditions that cause lameness. They include: 

•  Hoof abscesses

•  Sole bruising

•  Navicular disease

•  Laminitis

•  Osteochondrosis desicans (OCD)

•  Tearing of tendons or ligament. 

All of these conditions have different clinical signs and carry different prognoses. 

There are many different instruments which are used to look for pathology in the horse’s leg.  Radiographs allow the bone structures to be visualized, allowing vets to find abnormalities such as bone fractures, cysts, arthritis and OCD.  Traditional radiograph machines provide an excellent resource. They are efficient and relatively inexpensive, and our clinic has a portable machine that we can bring to you and your horse. 

There are also digital radiograph machines, which project images onto a computer screen.  They are more expensive and not as widely used.  And as radiography does a great job at picking up problems in the bone, an ultrasound machine does a great job at finding problems in the soft tissues such as tendons and ligaments. It helps vets looks inside these tissues for weak spots or tears.  This is also a relatively inexpensive way to help diagnose a lameness problem.  The veterinarians at our clinic also carry portable ultrasound machines for your convenience. 

HOW CAN THE PAIN BE TREATED?

Once a diagnosis is made, your veterinarian will discuss treatment options for your horse, which can range from rest and rehabilitation to joint supplementation and possibly surgery.  It is critical to have your horse evaluated as soon as a problem is found.  Don’t just give Bute to your horse and keep running – you may cause further damage.  Lameness can be very confusing and even misleading, but with the help of your veterinarian and the use of appropriate tools, tests and instrumentation, a diagnosis can be made and your horse can receive the proper treatment which will hopefully lead to a full recovery.