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Ligament Injuries in Sporting Dogs
N. Clark, DVM
most commonly seen injury in active dogs is a torn ligament in the
knee. Dogs have the same bones and ligaments forming their knee
joint as people do and they can suffer the same type of injuries.
One of these ligaments, the anterior cruciate ligament (ACL) is
the structure that is most frequently damaged. This is a common
injury in football players, skiers, and other human athletes. Damage
to the ligament occurs when the knee is twisted during weight-bearing
or when the knee is hyper extended. In sporting dogs, the mechanism
of injury is similar and this can occur in the field during strenuous
activity. Dogs may also suffer a torn knee ligament during routine
activities such as retrieving a ball or chasing a squirrel. An injured
dog may vocalize and will usually hold up the affected hind leg.
This type of response is typical of a complete tear of the ligament.
A partial ACL injury can also occur as the ligament becomes damaged
over a more prolonged time without a major traumatic event. These
dogs tend to experience a more chronic, episodic lameness that worsens
after exercise. In both acute and chronic injuries to the ligament,
the result is instability within the knee joint. This instability
results in pain and lameness, with the possibility of arthritis
in the future. In fact, injury to the ACL is the major cause of
arthritis in the canine knee joint.
of ACL Injuries
of a dog with a torn ACL will often reveal a swollen, painful knee
joint. In acute cases, the knee may have fluid swelling within the
joint, termed joint effusion, or more commonly referred to as "water
on the knee". Dogs with chronic knee instability tend to develop
scar tissue, which appears as a firm swelling on the inside of the
affected knee. X-rays are used to support the diagnosis and to document
the extent of arthritic changes in the joint. The most reliable
diagnostic finding, however, is evidence of instability in the knee
(known as the "anterior drawer sign"). When a veterinarian elicits
a positive drawer sign, the lower bone of the knee joint, or tibia,
is moved forward relative to the upper bone, or femur. Basic anatomy
of the canine knee joint is shown in Figure 1. In some large or
heavily muscled dogs, it may be necessary to use sedation or anesthesia
in order to relax the joint enough to demonstrate the drawer sign.
of ACL Injuries
or working dogs require surgical stabilization of the knee in order
to have any chance of returning to their previous level of performance.
It is advisable to have the surgery performed within a few weeks
of the injury to reduce the chance of secondary arthritis in the
joint. Veterinary surgeons have employed a large number of surgical
procedures to stabilize the knees of dogs with ACL injuries. Many
different techniques have been reported with varying success. The
actual technique used will be determined by the dog's age and size,
whether the injury is acute or chronic, and most importantly, by
the surgeon's preference and experience. In sporting dogs, the
repair should be performed by an experienced veterinary surgeon
in order to enhance the chance that the dog can return to the field
and perform satisfactorily. It is important to note, however, that
there is no technique that will return an injured dog's knee joint
to normal and some degree of arthritis will occur after surgery
in most cases. The two major categories of surgical repairs used
for canine knee injuries are those where stabilization is achieved
inside the joint (intra-articular) and those done outside the joint
(extra-articular). Satisfactory results have been reported for both
forms of repair. The knee joint is explored in most cases with both
types of surgical procedures in order to remove remnants of the
torn ligament and to inspect for torn cartilage. One of the knee
cartilages, referred to as the medial meniscus, is commonly damaged
along with the ACL. Treatment of the torn cartilage is necessary
to prevent continued pain after surgery.
support of the knee is common following surgery in order to protect
the repair during the early healing process. A padded bandage or
light splint is used for no more than a week or two after surgery.
Following removal of the external support, physical therapy is begun
on the knee joint to help restore muscle tone and range of motion.
During the recovery period, the dog's exercise must be restricted
in order to prevent damage to the surgical repair. Only brief leash
walks are permitted and the dog is not allowed to run, jump or play
for a minimum of 8 weeks. This is a difficult time for most sporting
dogs that are accustomed to a high level of activity. Most veterinary
surgeons allow a gradual increase in exercise, with the majority
of dogs returning to full activity within 3 to 4 months after surgery.
Results are generally quite good when the injury is treated soon
after it occurs. Chronic cases with more advanced arthritic changes
at the time of surgery will tend to have less satisfactory results.
These dogs frequently exhibit stiffness or lameness after rigorous
exercise and may require medication for their arthritis. In colder
climates, some dogs may exhibit a more pronounced lameness during
the winter months.
only realistic means of preventing a knee ligament injury is to
keep your dog as fit as possible. Dogs that are too heavy and those
with other orthopedic problems, such as hip dysplasia, are at increased
risk for a torn knee ligament. As with any athlete, training programs
should begin with less strenuous activity that is increased in regular
intervals until peak performance is achieved. If a serious injury
occurs, consult your veterinarian as soon as possible. Prompt treatment
of an injury will improve the dog's chances for a satisfactory recovery.
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