Canine lameness problems make up a large percentage of the patients seen on a daily basis by small animal veterinarians. They are often subtle, and sometimes even intermittent, making diagnosis of the primary cause very difficult. This apparent lack of clinical signs can be due to the animal having been rested or the use of antiinflammatory drugs. Careful observation of the dog's gait, in conjunction with thorough physical, neurological and orthopaedic examinations, is the key to correct diagnosis. The veterinarian's aim is to evaluate the presence and severity of any deviation from the normal gait pattern and to do this they need to have a good idea of what normal is for particular breeds and ages of dogs.¹

Being able to gain the maximum benefit from a consultation with an owner and their pet is required in order to make a correct diagnosis. Owners are usually able to provide details about the duration and rate of progression of the presenting problem, the current exercise routine, specific triggers and their own long term expectations for the animal. They may also have noticed particular changes in behavior of the dog, for instance, reluctance to jump or peculiar ways that the dog may sit or lie down. Lastly, information on the dog's current diet is useful, as weight of the patient may be relevant and changes to the diet may be necessary once a diagnosis has been made.

After obtaining a full history, we can start assessing the patient. The clinical evaluation of gait involves observation of the dog's movements at the walk, and if possible at the trot and run. Negotiating stairs and other obstacles may be required in some instances. The person handling the animal should be competent and always try to find non-slip surfaces on which to show the animal's gait.

Gait abnormalities to look out for include ataxia (uncoordinated limb movements), paresis (reduced voluntary movement), dysmetria (improper estimation of limb rate and range of movement), weakness (muscular or neurological), spasticity (increased muscle tone), stiffness, lameness or mechanical problems. Nerve root signature secondary to compressive lesions on the spinal cord or at the level of the intervertebral foramen, can mimic musculoskeletal injury.^1-3

Some tips to follow when evaluating a dog for an orthopaedic problem are: always use the same order of checking details, observe the patient at both the walk and trot and repeat this gait assessment after completing your lameness examination, as you may have exacerbated the problem through manipulation of the affected limbs. Don't forget to investigate the contralateral limb, even in cases of unilateral lameness. In dogs with elbow dysplasia, for instance, up to 70% are bilaterally affected, but most only present with lameness in one forelimb.⁴ Always try to leave the most obviously affected limb until last. Work from distal to proximal on the limbs and check the entire spine, including cervical and lumbosacral regions. It is preferable to do this before starting on the limbs, as dogs often lie down once you start to examine their limbs. A common mistake is to forget to check the sesamoid bones - lameness caused by sesamoid problems (fractures or bipartite sesamoids) is usually mild, but pain on firm pressure over the palmer or plantar surfaces of the paw will give some clues as to this diagnosis.^1,2

With the above information, the veterinarian should be able to categorize the patient into either an orthopaedic or neurological lameness and identify which limb or limbs are worst affected. With orthopaedic problems, points to take note of are: asymmetry of limbs, muscle swelling or alternately, muscle atrophy, conformational abnormalities, joint effusion, crepitus, reduced range of motion within the joints and pain or stiffness during palpation.

Specific tests are then used to confirm the diagnosis. When using the stifle joint as an example: A painful, swollen stifle may well indicate the presence of cranial cruciate ligament disease. In order to confirm this condition, we need to look for signs of a weight-bearing lameness, a positive sit test and/or a meniscal impingement click. Under light sedation, we can assess the dog for a positive cranial drawer sign and/or cranial tibial compression test.⁵ Joint cytology and radiology are used to confirm the presence of osteoarthritis.⁶ With all this information the veterinarian can make a fair assumption of the diagnosis and the dog can be booked for corrective surgery.

Orthopaedic problems are often confined to specific breeds and age groups. In some instances, conditions affecting young dogs may be less prevalent once the patient has reached skeletal maturity and this information is useful when deciding on the treatment protocol. An example of this is a condition like panosteitis, which is a developmental condition in the long bones of juvenile, large breed dogs, particularly German Shepherds. We know that this condition presents as a shifting lameness in dogs between the ages of 5 and 18 months. It is self-limiting, easy to manage and will not cause long-term disability in affected dogs.¹

Diagnostic imaging modalities effective in orthopaedic examinations include radiography which is easily accessible and useful as a primary imaging technique. Positional joint radiography can be used to diagnose ligament ruptures (which affect the stability of joints), as well as specific conditions such as osteoarthritis, osteochondritis dissecans (OCD) lesions, fractures or peri-articular calcifications. The limitations of conventional radiology include the lack of detail visible when superimposition of bones occurs and the lack of soft tissue detail. In these instances more advanced imaging techniques, like ultrasonography, magnetic resonance imaging (MRI) and computer tomography (CT), may be necessary.

Ultrasonography is helpful in the diagnosis of soft tissue abnormalities, foreign bodies, bone cysts and other lesions causing a discontinuity in bone integrity. It is the modality of choice for the diagnosis of tendon disorders and injuries which show up as a disruption to the fibre pattern, peri-fascial fluid or in some cases even the presence of a haematoma.⁷

MRI and CT scans are becoming more readily available and, although expensive, they have proven their worth in the diagnosis of conditions like elbow dysplasia (ED) and OCD lesions in the more complex joints, where bone superimposition makes identification of defects difficult to assess. Nuclear scintigraphy is less readily available, but useful no less for the diagnosis of early causes of lameness where increased osteophytic activity is present, but where radiographic abnormalities are not yet visible. This can be used in the diagnosis of early bone tumors or infections. Ideally animals should be under sedation when any of these advanced procedures are performed in order to minimize movement and ensure optimum detail in the images.

Another diagnostic tool that is largely underused in orthopaedic assessment is synovial fluid cytology or "joint taps." Synovial fluid collection is minimally invasive and inexpensive to perform. If a septic arthritis or osteomyelitis is suspected, then the same aspirate can be sent off for bacterial culture and antibiogram. From cytological examination of joint fluid we are able to differentiate degenerative conditions from septic or autoimmune conditions by studying the cell types and amounts of each type of cell under light microscopy.^6,8

In patients where the lameness is very vague and a specific cause cannot easily be identified, the value of repeat clinical examinations cannot be over-emphasized. Depending on the history and the complaint from the owner, the veterinarian may decide to reexamine the animal after exercise or once the effects of antiinflammatory drugs have completely worn off. Very nervous animals may also be easier to examine once they have calmed down or when not in the presence of their owners. In the majority of cases, where a thorough orthopaedic assessment has been performed in a logical manner, a correct diagnosis will be made and appropriate treatment can then be instituted.

References

VIN editor: References 5 and 8 are duplicates.

1.  LaFond E, Breur GL, Austin CC. Breed susceptibility for developmental orthopedic diseases in dogs. J Am Anim Hosp Assoc. 2002;38:467–477.

2.  Gordan-Evans WJ. Gait analysis. In: Tobias KM, ed. Veterinary Surgery Small Animal. St. Louis, MO: Elsevier Saunders; 2012;1190–1196.

3.  Leach D. Locomotion analysis. In: Bojrab MJ, ed. Disease Mechanisms in Small Animal Surgery. 2nd edition. Philadelphia,PA: Lea and Febiger; 1993:1112–1118.

4.  Hazewinkel HAW. Elbow dysplasia; clinical aspects and screening programs. In: Proceedings of the 28th World Congress of the World Small Animal Veterinary Association. Bangkok, Thailand; 24–27 October 2003:612–615.

5.  Slocum B, Slocum TD. Knee. In: Bojrab MJ, Ellison GW, Slocum B, eds. Current Techniques in Small Animal Surgery. 4th edition. Baltimore, MD: Williams and Wilken; 1998:1186–1244.

6.  Lozier SM, Menard M. Arthrocentesis and synovial fluid analysis. In: Bojrab MJ, Ellison GW, Slocum B. Current Techniques in Small Animal Surgery. 4th ed. Baltimore, MD: Williams and Wilken; 1998:1057–1062.

7.  Kirberger RM. Musculoskeletal ultrasonography. In: Proceedings of the 28th World Congress of the World Small Animal Veterinary Association. Bangkok, Thailand; 24–27 October 2003:359–362.

8.  Slocum B, Slocum TD. Knee. In: Bojrab MJ, Ellison GW, Slocum B, eds. Current Techniques in Small Animal Surgery. 4th edition. Baltimore, MD: Williams and Wilken; 1998:1186–1244.