The veterinary profession is currently witnessing an increased
demand from our clientele for information concerning performance of the
canine athlete. The expectations come as a result of the scientific advancements
in human sports medicine. The canine athlete can present uncommon challenges
to the general practitioner.1
Athletic Levels
Evaluation of performance, conformation, or lameness is dependent upon
the expectations of the individual animal. If the pet owner is only interested
in companionship, minimal stress will be put upon the body. As the athletic
demands of the owner increase there is a proportional increase in the physical
demands placed upon the animal's body. These increased demands placed upon
the animal introduce a higher risk of injury.
In athletic competition, the body is operating at its physical limits
in an organized event. The animals must be prepared for the rigors of competition,
supervised during the competition, and cared for appropriately following
their workout.
Locomotion
Motion is the one common component of all athletic competition. Motion
is a result of a combination of nerves stimulating muscle to move bone.
Abnormal motion occurs when this chain of events is disrupted. Locomotion
of an animal is described as its gait. The walk, trot, and gallop are three
forms of gait. The walk and trot are symmetrical gaits. In this type of
gait the movements of the right side mirror the movements of the left side.
The gallop is an example of an asymmetrical gait2, whereby the
limbs of one side move in a different pattern then limbs on the other side.
Lameness
Lameness is defined as a variance from normal gait. There are two types
of lameness: anatomical and pathologic. Anatomical lameness may not necessarily
be from pain, and can be genetic or acquired. Chondroplasia in the Alaskan
Malamute is a genetic condition that would produce a lameness. An example
of an acquired lameness would be rickets as a result of a Vitamin D, calcium,
or phosphorus deficiency. Pathological lameness can be neural or musculoskeletal.
Cauda equina lesions are an example of a neural lameness. Musculoskeletal
lameness is usually caused by pain.3 Two diagnostic tools to
assess lameness are gait analysis and the physical exam.
Gait Analysis
Canine locomotion can be compared to a symphony orchestra playing a
composition. "All parts must blend into a harmonious pattern, from the
gentle sway of the head and tail for balance to the coordinated efforts
of each limb and body muscle to accomplish its special function. Conversely,
also like an orchestra, if all movements are not attuned to the whole,
a major fault should be evident" (Roy 1971).4
The canine structure is divided into segments when analyzing motion.
The axial vertebral column is made up of many joints and is divided into
anatomical segments. The cranial segment is the head, followed caudally
by the neck (cervical), thoracic, abdominal (lumbo-sacral), and tail. The
appendicular segments are the front legs and the back legs. These are subdivided
into smaller segments by the leg joints: shoulder, elbow, carpus, hip,
stifle, tarsus & phalanges. Locomotion as a whole is a result of the
individual movements of these segments. Gait analysis is used to assess
the movement of each of the individual joints and how they affect locomotion.
Quantitative gait analysis assigns numerical values to motion and includes
the application of kinetics and kinematics. The force plate is an example
of kinetic analysis being used to assess lameness. The numerical values
of the ground reaction forces are used to determine variances of gait.
Video analysis is used to assess the kinematic parameters of locomotion.
With kinematic analysis, linear parameters of movement can be measured
to assess horizontal and vertical motion. Also, angular parameters can
measure the degrees of movement of the joints to analyze specific joint
motion.
Subjective gait analysis is the most common diagnostic tool to assess
lameness. This should be done prior to any physical palpation. It starts
by observing the animal while it is still, looking for conformational abnormalities
or abnormal stances. For example, does the dog seem to hold one leg up
or put most of its body weight on a particular leg. After these observations
are noted the animal is analyzed while moving. The gait is a description
of a particular series of leg and body movements used for locomotion. In
the trot one front leg and the contralateral rear leg are in support and
that is followed by the other front leg and its' contralateral rear leg
in support. This is the gait pattern that can give the best picture of
abnormal gait. If one of the segments is impaired the gait will be out
of balance.
The patient is observed moving in a straight line toward and then moving
away from the clinician. Next it should be assessed moving in a straight
line from the right side and then the left side. Then it should be observed
moving in a circle, once clockwise then counter-clockwise.
Most gait abnormalities can be detected with subjective gait analysis.
A dog with a lesion causing severe sharp constant pain will carry the limb
and keep the weight off it when lying down. A dull aching pain will produce
a limp during the gait analysis. A lesion that produces a small pain that
occurs in certain phases of locomotion allows the dog to adjust their gait
for relief. This altered gait can lead to subsequent orthopedic problems.
Physical Examination
The physical examination is a hands-on procedure used to look for musculoskeletal
abnormalities and pain. The clinician can look for anatomical abnormalities
or asymmetries to help find the source of lameness. If one joint is injured
it will sometimes be larger or hotter than the unaffected joint.
The primary function of the physical exam is to detect the source of
pain causing the lameness. The axial skeleton can be checked to determine
any vertebral pain or abnormalities. Usually the patient will elicit a
pain response when the affected area is manipulated. The neck is checked
by flexing and extending it in the various directions. The thoraco and
lumbar vertebrae can be tested by applying pressure along-side each vertebra
starting at the cervico-thoracic junction and working caudally to the tail.
In the appendicular skeleton every joint should be palpated in the different
planes of motion, beginning with the phalangeal joints working proximally
to the axial skeleton. Each joint should be flexed and extended cranially
and caudally, then medially and laterally, and then torsion should be applied
to the joint in both a positive and a negative direction. The examination
should begin with the areas not showing lameness, finishing with the area
of suspected lameness. Starting the exam with the sound limbs helps to
determine the pain level of the patient. Once the primary cause of lameness
is determined, treatment and therapy are initiated to address this problem.
Pain is an important performance inhibitor. When compared to the active
dog, subclinical pain of the companion pet does not greatly affect the
musculoskelatel system. Usually anti-inflammatory therapy is sufficient.
In the physically active or competitive animal any pain or lameness should
be addressed as soon as possible before these problems affect performance.
Gait analysis and the physical examination are two useful diagnostic tools
for the veterinary clinician working with the animal athlete.
1. Gillette, R.L., Zebas, C.J., Performance of the
Canine Athlete. ACSMA Newsletter 2(2)2-3, (1996).
2. Hildebrand, M, Symmetrical gaits of Dogs in relation
to body build. Journal of Morphology, 1968;124: 353-360.
3. Sumner-Smith, G, Gait Analysis and Orthopedic
Examination. In Slatter, D.S. (ed): Textbook of Small Animal Surgery
2nd ed, W. B. Saunders, Philadelphia, (1993).
4. Roy, W. E., Examination of the canine locomotor
system. Veterinary Clinics of North America, 1 1971(1): 53-70.
