Effects of intra-articular administration of dimethylsulfoxide on chemically induced synovitis in immature horses.

The research study investigates the impact of using dimethylsulfoxide (DMSO) to treat chemically induced inflammation of joint tissues (synovitis) in young horses.

Background

• In this study, researchers focused on understanding how dimethylsulfoxide (DMSO) can affect synovitis, an inflammation of the joint tissues caused by the injection of Na-monoiodoacetate.
• Six weanling horses were used in the study and their middle carpal (wrist) joint of both forelimbs were used. They were then observed for lameness, joint effusion, and changes in their synovial fluid.

Methodology

• The middle carpal joint of each horse’s forelimb was injected with 50 mg of Na-monoiodoacetate to induce synovitis.
• After eight days, synovial fluid was obtained and the right middle carpal joints were injected with DMSO in a lactated Ringer solution. The same was done on the control left limb, however, without DMSO.
• These procedures were repeated on days 11 and 14, resulting in a total of three treatments.
• Using the Kaegi gait analysis, the horses’ lameness was objectively measured on days of 7 and 17.
• On the final day (day 17), synovial fluid, synovial membrane, and articular cartilage specimens were collected for further analysis.

Findings

• 12 hours after Na-monoiodoacetate was injected into all joints, joint effusion (fluid accumulation causing swelling) was noticeable.
• Mild lameness was observed at 24 hours but generally resolved by 72 hours. However, no significant differences were noted between the treated limbs and the control ones.
• Hyaluronic acid concentrations and WBC counts in synovial fluid increased significantly following Na-monoiodoacetate injection and stayed above baseline values throughout the study period, showing a continuous immune response and synovial fluid recovery.

Implications

• The study suggests that DMSO might not have a significant effect on reducing synovitis in horses, given that no significant difference in lameness was observed between the treated and the control limbs.
• However, the increased hyaluronic acid concentrations and WBC counts in synovial fluid might indicate a beneficial role for DMSO in promoting healing and reducing inflammation in synovitis, although further long-term studies are required to confirm this.