The influence of corticosteroids on sequential clinical and synovial fluid parameters in joints with acute infectious arthritis in the horse.

This research investigates the impact of corticosteroids on the progression of acute infectious arthritis in horses by looking at clinical symptoms and changes in synovial fluid. The study finds that corticosteroids can mask the clinical symptoms of arthritis for up to three days, however, changes in synovial fluid become apparent earlier.

Study Design

• The researchers induced infectious arthritis in one tarsocrural joint of six horses by injecting 1 ml Staphylococcus aureus-saline suspension containing 200 mg methylprednisolone acetate.
• The contralateral joint of each horse was treated with 1 ml saline and 200 mg methylprednisolone acetate, without bacteria, serving as a control.
• The aim was to observe the effects of corticosteroids on the clinical signs of infectious arthritis and associated changes in synovial fluid, in order to separate the effects of the steroid injection from the infection alone.
• This observation would help to make an early diagnosis of the infection.

Observation and Findings

• The progression of infectious arthritis was assessed over a period of nine days through clinical examination and sequential synovial fluid analysis.
• The corticosteroids masked the clinical signs of the disease in some horses up to the third day, even though changes in the synovial fluid were apparent earlier.
• Initially, cellular changes, specifically the increase in leukocyte counts, preceded biochemical changes after the infection was established.
• Persistent neutrophilia, cell presence of over 90 percent, along with a pH under 6.9, were the most consistent observations for infected synovia.
• Total protein values were seen to be lower in infected joints treated with corticosteroids than in those without, despite a progressive rise in total protein concentration in all the joints throughout the experiment.
• Measurements of serum and synovial glucose discrepancy and synovial lactate have limited diagnostic value since significant increases due to the corticosteroids were documented in the control joints.