Evaluation of the effects of intra-articular injection of dimethylsulfoxide on normal equine articular tissues.

To evaluate the effects of intra-articular injection of dimethylsulfoxide (DMSO) on normal equine articular structures, 7 adult horses with clinically normal carpi were allotted to 2 treatment groups (group A, n = 4; group B, n = 3). In each horse after collection of synovial fluid samples, the right antebrachial carpal and middle carpal joints were aseptically injected with 2 ml of a 40% solution of 90% medical grade DMSO in lactated Ringer solution, and the corresponding joints of the left forelimb (controls) were injected with 2 ml of lactated Ringer solution. In group-A horses, 2 ml of synovial fluid was obtained prior to injections of 40% DMSO at 24 hours and 72 hours, for a total of 3 injections. At necropsy, synovial fluid, synovial membrane, and articular cartilage specimens were obtained. Group-B horses were injected with 40% DMSO in the same sequence; however, the series was repeated following a 1-week interval. Clinical evaluation of these horses revealed no evidence of carpal inflammation associated with any injection in any group. Synovial fluid analysis of DMSO-injected and control joints revealed insignificant differences in leukocyte counts and total protein content. There was no evidence of cartilage degradation on gross, histologic, or histochemical evaluation of any of the joints. Intercellular matrix staining of the articular cartilage failed to reveal any observable difference in glycosaminoglycan content between injection with DMSO or lactated Ringer solution.