Hypothesis 3- Inflammatory Joint Disease of Infectious Cause

Facts of the case leading to this hypothesis:

     Dog lame in hind limbs, right worse than left
     Uncomfortable sitting
     Reluctance to climb stairs
     Worse in AM, after exercise
     Mild lameness (1 out of 4) in hind limbs
     Pain reaction in hip joints
     Reduced range of motion in hip joints

Summary of Infectious Arthritis:

     Inflammatory joint disease is characterized as infectious or non-infectious 
arthritis.  Infectious arthritis can be caused by a variety of organisms: 
bacteria, spirochetes, mycoplasma, rickettsias, viruses, fungi and protozoa. 
Joints are common destinations for these organisms due to their rich blood 
supply and importance as a phagocytic tissue.   Infection by local or 
hemtogenous means causes inflammatory changes in the synovial 
membrane. These changes often lead to cartilage damage. Usually involves 
1 or 2-5 joints, larger joints (i.e. hips) more likely to be involved, larger dog 
more likely.  Joints may be painful, hot and swollen and with a reduced 
range of motion on examination. Joint effusion may be present. Usually see 
signs of systemic illness (fever, leukocytosis, anorexia).  

How to diagnose:

     Synovial fluid on joint tap- frequently bloody, neutrophilia, culture 
     Radiographs- thickened synovial membrane, distended joint capsule, 
widening of joint space due to effusion, periosteal proliferation

Treatment:
 
      Antibiotic treatment based on culture results if for bacterial causes

This hypothesis most unlikely of the three.  No joint effusion or signs of 
systemic illness were seen.  No evidence of local infection of joint.