Anti-inflammatory effects of topically applied dimethyl sulfoxide gel on endotoxin-induced synovitis in horses.

This research discusses the positive effects of using dimethylsulfoxide (DMSO) gel, applied topically, for reducing inflammation in horses experiencing synovitis due to an occurrence of lipopolysaccharide (LPS).

Study Design and Procedure

• The researchers planned and executed a double-blinded, crossover, paired research study involving six healthy adult horses, employing a resting period of one week. A total of 12 carpi or joints were allocated between two groups—in the first one, DMSO was applied (six horses), while the other group acted as control (six horses).
• Both groups received an injection of 1.3 ml (0.0125 ng/dl) LPS into the mid-carpal joints to simulate synovitis condition. The DMSO group had a 90% DMSO gel (quantity of 15 g) applied after LPS injection and thereafter every 12 hours for a duration of 60 hours. The control group received only LPS injection, with no DMSO gel application.

Evaluation and Results

• The horse’s health conditions were periodically evaluated through lameness examinations and synovial fluid analyses, observing variables like total and differential WBC count, and total protein concentration. These tests were conducted every 12 hours, for 60 hours post the LPS injection.
• The researchers discovered the DMSO group showed a significantly lower mean WBC concentration at the 24-hour mark, and exhibited a downward trend even at 36 hours, compared to the control group. Also, total neutrophil count was significantly lower in the DMSO group at the 24-hour mark.
• DMSO was detected in the synovial fluid of 5 of the 6 joints where it was applied, and in the bloodstream of one of the six horses.

Conclusions

• The researchers concluded that topically applied DMSO gel successfully penetrated the synovial fluid, reduced inflammation and was able to be detected. This finding implies a potential therapeutic use of DMSO gel for conditions like synovitis in horses.