Synovial fluid analysis, including evaluation of white blood cell counts and matrix metalloproteinases -2 and -9 (which degrade articular cartilage), can be employed to monitor effect of treatment and predict survival in horses with septic arthritis, reported researchers from the Matrix Biology Research Group, University of Bristol School of Clinical Veterinary Science, in the United Kingdom.

Septic arthritis, an inflammation of the joint caused by bacteria, is a career-limiting condition that rapidly results in the widespread destruction of articular cartilage within the affected joint. Septic arthritis is an expensive condition to treat and is associated with a 10-15% mortality rate, despite aggressive treatment efforts.


This study evaluated 39 synovial samples from 32 horses diagnosed with septic arthritis and 39 "normal" samples from horses euthanatized for non-orthopedic conditions.

Levels of the proenzyme (i.e., the inactive precursor) form of matrix metalloproteinases -9 and white blood cell counts were over ten times higher in horses with septic arthritis than normal horses and decreased following treatment. Further, both measurements taken at referral predicted survival as levels were 1.5 times higher in horses that were ultimately euthanized compared to horses that lived.


In addition, the ratio of the proenzyme forms of matrix metalloproteinases -9 and -2 was identified as a useful marker for monitoring treatment of septic arthritis and as predictor of survival.

No relationship between the time of injury and time to referral was identified. This was a novel finding since most stud