Lameness exam: what am I missing? (Proceedings)

November 1, 2010

The ability to diagnose the cause of a lameness is essential to the small animal clinician. In our day to day practice settings, dogs and cats present with a variety of lamenesses. Many of these problems resolve with rest, or a diagnosis is readily available (cut pad, ingrown nail, etc?).

The ability to diagnose the cause of a lameness is essential to the small animal clinician. In our day to day practice settings, dogs and cats present with a variety of lamenesses. Many of these problems resolve with rest, or a diagnosis is readily available (cut pad, ingrown nail, etc…). However, there is a small group of cases in which an obvious cause of the lameness is not available to the clinician. It is this group of animals which will be examined in this discussion and these dogs and cats, although small in number, can soon become a major drain on your time and patience. As with any case, an accurate history, signalment and a complete physical examination are the cornerstones to our data base.

Once a lameness persists in a patient and your initial management fails to resolve the problem you are faced with a different situation. To effectively work up this type of case, there are some important things to remember. First and foremost, allow adequate time to assess the animal. This is true even if you have seen the dog or cat a number of times previously. This is not the case to schedule a 10 minute appointment in-between surgeries.

History and Signalment:

A lameness may be sudden or acute in development or slow and insidious in onset. Be sure to obtain the following information from the client: (1) The owner's complaint, (2) How and when did the problem develop (3) Overall duration of the problem (4) Does the lameness vary in severity (5) Previous treatments and associated response (6) Additional information such as diet, environment, previous injury, etc…

Physical Examination:

A complete physical examination should be conducted. Remember, the problem is a lame animal, not just a lame leg. Many persistent lamenesses are manifestations of diseases that affect other systems of the body. The exam has two major aspects, observation and palpation of the patient. Observation should start in the exam room but is not limited to this confined space. Examine the conformation, use of limbs, swellings, etc. Also, evaluate the animal's attitude. At this time you can get an overall impression of the animal's general body condition. Following a brief TPR and basic exam (temp, chest auscultation, and general examination of the eyes, ears, nose and mouth), observation of gait should be done.

Evaluate multiple gaits including a walk and trot. Lameness in dogs and cats is manifested in various ways. If one or more limbs do not perform to their average capacity in supporting the animal, the sound limbs must accept increased responsibility of weight-bearing. This results in a shifting of the center of gravity toward the more sound limbs. Oscillations of the center of gravity are then greater than normal producing a visible imbalance "what you visualize as the lameness." Dogs will show the same gait abnormalities as horses. One example is with a forelimb lameness, where the dog will lower the head when the sound limb is on the ground and will throw the head up when the lame limb is in the stance phase. Also unilateral rear limb lameness may be associated with a "hip hike" of the affected limb and extension of the head during the stance phase the affected limb. Dogs will also place a lame limb forward during standing and will point "toe out" the paw of the affected limb. Often less weight is supported through the lame limb which can be picked up more easily than the contralateral sound limb.

At this point, a brief neurological exam is performed. While a more complete exam may be necessary later, at this time one should assess cranial nerves, neck movement and proprioceptive responses in all limbs. Also check myotactic reflexes.

Neurological short list

          - conscious proprioception

           • nervous system involvement vs. musculoskeletal system

          - mental depression or severe acute pain may be causes of an "apparent" neurological deficit (ACUTE FRACTURE , MENTAL DEPRESSION)

          - Pain sensation, reflexes

           • withdrawal does not equal conscious & voluntary!

An important key to the physical examination is that it is a "hands on" event and close attention should be paid to body symmetry.

When starting the palpation be sure to be systematic and follow the same pattern each time. Remember to divide the animal into two halves and always compare the two halves against each other. When palpating muscles and tendons with finger pressure; use enough pressure to blanch your fingernails. Isolate joints when evaluating them for range of motion and pain.

Remember there are some common mistakes we all fall victim to:

General Mistakes made during your examination:

     1. Failure to do a complete physical exam

            a. Place the animal in lateral recumbency

            b. Take the animal out of the exam room

     2. Having a preconceived diagnosis

     3. Not allowing enough time and patience

Specific Mistakes

     1. Failure to perform distant exam

            a. observe walk and trot from all directions

            b watch sitting, rising, stairs, circling

     2. Failure to check for symmetry while standing

            a. muscle atrophy / tone

            b. joint / soft tissue swelling

     3. Failure to palpate for spinal pain

     4. Failure to palpate for muscle pain

     5. Inappropriate manipulation for cranial drawer

     6. Inability to detect hip laxity

     7. Inability to detect joint effusion

     8. Failure to systematically evaluate the shoulder region

     9. Failure to assess elbow rotation to evaluate medial and lateral restraints

Examples of Difficult Forelimb Lameness Cases

     1. Immature large breed dogs

           • Consider failure of endochondral ossification as a strong possibility

           • Watch out for bilateral disease, which can make the presentation very confusing

           • Do not forget panosteitis; it may be difficult to discern on radiographs

           • Common error is to assume it is shoulder OCD, when in fact many more dogs are presenting with elbow abnormalities.

     2. Immature small breed dogs

           • Congenital luxations

           • Subluxation due to premature physeal closure

     3. Mature large breed dogs

           • Degenerative joint disease

           • Systemic diseases which are not skeletal in nature

               • Causing Neuropathies or Myopathies, either inflammatory or non-inflammatory

           • Panosteitis

           • Cervical cord lesions

           • Inflammatory joint diseases

           • Neoplasia, including brachial plexus tumors

     4. Mature small breed dogs

          - Degenerative joint disease

           • Systemic diseases which are not skeletal in nature

               • Causing Neuropathies or Myopathies either inflammatory or non-inflammatory

           • Medial shoulder luxations

           • Cervical cord lesions

           • Inflammatory joint diseases

           • Neoplasia, including brachial plexus tumors

These lists are not exhaustive but they provide causes for lameness which are often not considered. The easiest way to generate lists like this is to systematically go through the DAMNIT algorithm.

Examples of Difficult Rear Limb Lameness Cases

     1. Immature large breed dogs

          - Of course hip dysplasia should always be considered, but a common error is to assume every case is lame due to hip dysplasia. Remember many dogs have radiographic evidence of hip dysplasia but that is not the source of their lameness.

          - Consider failure of endochondral ossification as a strong possibility

          - Watch out for bilateral disease; this can make the presentation very confusing

          - Do not forget panosteitis; it may be difficult to discern on radiographs

          - Consider cruciate injuries; more are appearing in young large breed dogs.

          - Patellar luxations

     2. Immature small breed dogs

          - Patellar luxations should always be considered, but a common error is to assume that every dog is lame due to luxating patellas. Not always true.

          - Hip dysplasia does occur as a clinical problem in small breed dogs.

     3. Mature large breed dogs

          - Degenerative joint disease which is almost always secondary (Cruciate injuries, tarsal OCD etc…)

          - Systemic diseases which are not skeletal in nature

               • Causing Neuropathies or Myopathies, either inflammatory or non-inflammatory

          - Panosteitis

          - Inflammatory joint diseases

          - Muscle strains (eg: iliopsoas)

          - Neoplasia

          - Spinal cord lesions

     4. Mature small breed dogs

          - Degenerative joint disease

          - Systemic diseases which are not skeletal in nature

               • Causing Neuropathies or Myopathies either inflammatory or non-inflammatory

          - Spinal cord lesions

          - Inflammatory joint diseases

          - Neoplasia

Difficult Cat Lameness Cases

Less often we are faced with difficult lameness in cats. By far the most common causes for problems in the cat are abscesses, and foot (specifically nail) problems. However, there are cases in cats which can be frustrating.

     1. Inflammatory Muscle Disorders

     2. Osteoarthritis (Degenerative Joint Disease)

           • Hip dysplasia

           • Old Trauma

           • Ossification of the menisci

     3. Patellar Luxations

     4. Neurology Manifestations of Systemic Disease

          - IVDD

          - Diabetes Mellitus

          - FIP

          - Felv