Lameness Exams

 

          Lameness is the most common health issue that affects the usefulness of our equine companions.  Like humans, the more strenuous the exercise, the more likely lameness issues are to occur.   As veterinarians, it is standard practice to classify lameness into five grades from 0-5:

 

0. No signs of lameness under any condition.

 

1. Difficult to observe and inconsistently apparent.

 

2. Difficult to detect at a walk or trot in a straight line, but is inconsistently apparent under particular circumstances (eg. under saddle, hard surface, circle , incline).

 

3. Consistently obvious at a trot in all circumstances.

 

4. Lameness is obvious with a marked head nod, or hip hike, and /or a shortened stride.

 

5. Non-weight bearing lameness.

 

     We can divide lameness problems into two classes:  ACUTE and CHRONIC.  Acute lamenesses occur at any age and are usually the result of a recent injury.  Minor causes would include simple bumps and bruises, while more serious lameness may be due to joint sprains, tendon or ligament strains, punctures into joints, tendons or tendon sheaths, muscle injuries and worst of all, bone fractures.

     CHRONIC lamenesses are of a more long standing nature and develop over time.  Many are due to wear and tear over a long period.  Horses used only for easy, light riding rarely develop chronic lamenesses until they are very old.  On the other hand, horses involved in strenuous activities can develop wear and tear injuries at a young age.  In fact, if horses are pushed too hard at too young of an age, they can be at very high risk.  

     So as an owner, how should you handle a lameness concern?  With an ACUTE LAMENESS, obviously it depends on the grade of lameness. With a grade-5, you have an emergency.  Call your vet right away as early diagnosis and treatment may make the difference of saving the horse or not.  While yo wait for your vet, try to keep the horse from moving around.  If he will stand still by himself, just leave him where he is to stand quietly.

     With a Grade 3 or 4, you likely do not have and emergency, but you should try to get the horse examined today if you can.

     With a Grade 1 or 2, usually you would be safe to wait a day or two to see if the horse improves.  Keep in mind, however, you need to watch carefully to see that the horse in not getting more lame.  If the lameness does not improve daily, get help.

 

     CHRONIC LAMENESSES are never an emergency, but often early diagnosis and treatment have a better chance of returning the horse to soundness. With some chronic lameness conditions, even experienced veterinarians may have some degree of difficulty in determining what the cause of the lameness is.  It is not uncommon to have a chronically lame horse brought to us, and the owner or trainer says he/she thinks the horse is lame in the shoulder, or hip or some specific place on a leg.  In reality, in almost all cases, all one can determine by watching the horse move is which particular leg the horse is lame on.  This is where the diagnostic challenge begins.  Usually it is not simple, or the owner would have likely already figured it out.

     The further down the limb one gets, the greater the likelihood that the injury is down there.  That is, if one considers, the front limb, the most common location for pain to occur would be in the foot, followed next by the pastern, ankle and cannon areas, less in the knee (carpus) , and even less in the elbow and shoulder.  Similarly, in the hind limb, the foot, pastern, and ankle would be high up on the list followed by the hock, stifle and hip.

     Certain job descriptions are more likely to lead to particular lameness issues.  The cutting horse or reigning horse puts tremendous stress on it's stifles, hocks and hind ankles.  The racing thoroughbred or polo horse tends to stress the front ankles due to the speed work.  Jumpers place great demands on their hocks and front ankles and suspensory ligaments.  Dressage horse stress their hocks and suspensories.

     Obviously, if a human has pain causing lameness, he/she can tell the doctor, "it hurts right here when I do this".  We are not so lucky in our profession, but we have a number of things we do to try to diagnose the source of pain in our patients.  Often there is no outwardly visible clue on the limb.  Using our fingers and hands to feel the superficial and deep structures in the limb and/or foot may detect the source of the pain.  Sometimes by flexing, bending or stressing individual joints or areas on the limb we can elicit a painful response.   If no source of the pain can be found, our next step is to perform DIAGNOSTIC NERVE BLOCKS.  Here, using small amounts of injectable local anesthetic, we anesthetize (freeze) specific areas of the limb.  We usually start at the foot and work upward using a systematic series of injections basically dividing the limb into small segments. After each injection has had time to freeze that particular segment, the horse is trotted out to see if the lameness has improved or disappeared.  If it has improved, then we know that is the segment of the limb which requires a closer look.  If no improvement is noted, then we move up the leg to the next injection location.

     Once we have narrowed it down to a fairly specific area with our nerve blocks, we then move on to other diagnostic tools.   Radiographs (X-rays) are used to look at bones and some soft tissues often in and around joints.  Diagnostic ultrasound is used to visualize soft tissue structures like ligaments, tendons, and cartilage.  Usually, using the local nerve blocks along with radiographs and/or ultrasound, we can locate the source of the lameness. Sometimes, however, even after all this is done  a definitive diagnosis is not reached.

     Very difficult cases may require referral to a large center like a university teaching hospital for further diagnostic work up using CT SCANS, MRI, or  NUCLEAR SCINTIGRAPHY.  In our area, referral centers are fairly close by in Washington State where we send cases.   

 

   Dr. Jessica Wales