Feb 03 2014

Cruciate Ligament Injury (Ruptured ACL)

My ankle is feeling much better, thanks for asking.  As promised (though delayed from a little icy precipitation), I thought I would quickly tackle a very common disease in medium to large breed dogs: Cruciate Ligament Rupture.  In humans, the common term is a ruptured ACL (ANTERIOR Cruciate Ligament), but in dogs we call it a ruptured or torn CRANIAL Cruciate Ligament.  The difference is only that we stand upright and therefore our knees are oriented anterior/posterior (front to back) and dogs knees are oriented cranial/caudal (head to tail).


In the diagram above, left is towards the head and right is toward the tail.  The rupture is shown in the right-hand picture.  When this happens, the knee is unstable front to back.  Due to the “dog-leg” portion of the dog’s leg, the tibia keeps moving forward under the femur every time the dog takes a step.  This bone-on-bone grating is very painful and makes the dog limp and cry out in pain.


Diagnosis of this condition almost always involves proving the instability of the knee exists.  Creating a “cranial drawer” sign by moving the tibia while the femur is stationary is definitive for a tear of the ligament.  As a side note – while this can be an injury during athletic exercises, this doesn’t have to come on all at once.  In fact, in overweight female dogs around 4-5 years old are more likely to present with a slow chronic lameness.


The only way to fix this is surgery.  Surgeries all consist of either making something to function in the ligament’s place or changing the angle of the dog-leg to make the slipping of the bone less likely.  While expensive, they are almost always effective at fixing both the injury and the lameness.

So, there you have it – the quick and dirty info on cruciate ligament disease.  #dogsdon’tplaysoccerbuttheycould

– Doc Cleland

muller01 | College Park Vet Blog

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