Diagnosing cranial cruciate ligament pathology - Veterinary Medicine
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Diagnosing cranial cruciate ligament pathology
Not all dogs with cranial cruciate ligament pathology have palpable stifle instability. Here are a few examination skills and diagnostic tools to help you make an early diagnosis.


VETERINARY MEDICINE


SIGNALMENT

Dogs of any breed, sex, or age can present for lameness resulting from cranial cruciate ligament pathology; however, a breed predisposition has been reported in Labrador retrievers, Chesapeake Bay retrievers, rottweilers, mastiffs, American Staffordshire terriers, Neopolitan mastiffs, Akitas, and Saint Bernards.12,13 Neutered males and spayed females are at increased risk compared with their intact counterparts.10,12,13 Larger breeds and obese dogs have an increased risk of cranial cruciate ligament disease.10 Cranial cruciate ligament rupture can occur at any age, but larger breeds tend to present at younger ages than do smaller breeds.13

HISTORY

The presenting history of patients with cranial cruciate ligament pathology is varied. The onset varies from peracute after a traumatic or athletic injury to slow and insidious, typical of cranial cruciate ligament disease. Dogs with an acute onset of nonweightbearing lameness often improve over several weeks as the inflammation subsides, particularly with rest and nonsteroidal anti-inflammatory drugs (NSAIDs). But point out to pet owners that this initial improvement does not indicate a resolution of the condition. Commonly, dogs with early or minor cranial cruciate ligament pathology will initially return to near normal function with time, rest, and NSAIDs only to present several weeks or months later with a more severe and persistent lameness. In many cases, this history indicates progression to a complete cranial cruciate ligament rupture or the development of a secondary meniscal injury.

GAIT EVALUATION

Gait evaluation is used to detect lameness and confirm the limbs involved. In some instances, it can strongly direct you toward a specific joint as the source of the lameness. Closely observing dogs standing still, walking, trotting, running, and sitting and rising gives you a great deal of information regarding cranial cruciate ligament function and whether a problem is unilateral or bilateral. Have a trained assistant lead the patient through the gait evaluation so you can see the appropriate gaits.

Dogs with even subtle lameness often lean away from the affected limb while standing. The degree of lameness noted at a walk varies from no lameness to nonweightbearing. Often, lameness that is absent at a walk is evident when the dog is trotting or running. Additionally, circling the dog around you may expose a subtle lameness because weightbearing is shifted toward the inside leg. For example, subtle left pelvic limb lameness may be exposed when circling the patient around you counterclockwise.


Figure 3 Palpate both stifles simultaneously to compare muscle mass and determine whether periarticular fibrosis, joint effusion, and warmth are present.
Perform a sit test by having the patient sit and rise while facing away from you.14 Dogs with stifle or tarsal pathology will often abduct the affected limb while sitting to avoid the discomfort of the full tarsal and stifle flexion necessary for normal sitting. Alternatively, some dogs will shift the affected limb slightly cranially to diminish flexion of these joints. While you still must perform a complete orthopedic examination, this finding directs you toward stifle or tarsal pathology as one source of the pelvic limb lameness. Dogs presented for bilateral pelvic limb lameness often shift their weight to the thoracic limbs while sitting and rising. In fact, many dogs originally presented for unilateral pelvic limb lameness will shift their weight similarly, which should make you highly suspicious of bilateral pelvic limb involvement.


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Source: VETERINARY MEDICINE,
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