Clinical Aspects of the Greyhound

Robert L. Gillette, DVM, MSE

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.

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 gait, 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. 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).

The canine structure is divided into segments when analysing 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 analyse 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 analysed 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 orthopaedic 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 musculoskeletal 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.

Performance Inhibitors

There are 3 general conditions that have a detrimental affect on performance:                     

Fatigue
Pain
Psychology (Drive)

Fatigue:

The moment fatigue sets in, it will begin to diminish the level of performance. Energy and focus is diverted away from the activity and utilized by the body to maintain function. Designing a training and conditioning program to suit the type of work or athletic event your dog competes in can minimize the affects of fatigue. The program should address: Genetics (breeding), Training, Conditioning, Nutrition, and Health Care.

Pain:

The effects of pain on performance usually go unnoticed. The dog has the ability to minimize pain by altering body movement in such a way that the abnormality is unperceivable by the naked eye. This altered movement created by the primary cause of pain puts altered forces upon the rest of the body. In the athletic or active dog these abnormal forces lead to secondary and tertiary gait problems. This psychology could be a result of genetics or training, or it could be medical.  Both of the two previous affecters can alter the psychology or drive of the canine athlete. Sometimes the will to perform will over-ride these conditions.  This can be good for a single event, but can push the body past normal limits which can affect future performances. The effects of fatigue or pain will then act to divert attention away from the competitive performance or daily task. Before beginning any animal behaviour therapy the medical problems should be resolved.