Specialty Exam Results

	The joint fluid analysis indicates an acute injury to the stifle joint since the fluid is 
red in color, denoting hemarthrosis.  The good mucin clot indicates the absence of joint 
sepsis or immune-mediated disease process in the stifle.  Bacteria were not noticed in the 
fluid, again supporting the idea that sepsis is not the cause of the joint effusion or 
lameness.  The fluid cellularity is slightly increased and consists mainly of neutrophils 
and monocytes.  An acute injury incites an inflammatory response, the neutrophil being 
the principle acute inflammatory cell.  Monocytes are present to phagocytize any debris 
in the joint and clear up the joint hemarthrosis.  A chronic disease process in the stifle 
would produce clear joint fluid and show no evidence of hemorrhage.  

	The bloodwork indicated an acute inflammatory response due to the neutrophilia.  
The cells damaged when the cruciate ruptured release cytokines into the joint, which 
attract circulating neutrophils into the area.  There is a slight hypoalbuminemia that might 
be the result of the inflammatory response.  Inflammatory mediators released by the 
damaged cells and neutrophils cause the blood vessels to become more permeable.  These 
vessels are then able to leak albumin out of the circulation and into the tissues.  The very 
slight hypocalcemia is a result of the hypoalbuminemia since some calcium is bound to 
albumin in the circulation.  Taking into consideration the decreased albumin levels, the 
serum calcium is actually 10.7mg/dl and within the reference range.  

	The radiographs show caudal joint capsular swelling and a cranial displacement 
of the infrapatellar fat pad.  These changes indicate the presence of an effusion.  The joint 
space under the medial femoral condyle is reduced in width due to the increased mobility 
of the tibia.  The intact cranial cruciate acts to keep the tibia in place and prevents tibial 
rotation.  There is no evidence of osteophytes, which indicate a more chronic condition, 
or bone lysis, a hallmark of joint neoplasia.  The lack of bone pathology does not rule-out 
a cruciate rupture.

	Therefore, the special exam results support the hypothesis 2: acute cranial cruciate 
ligament injury with resulting inflammation.