Anti-inflammatory effects of topically applied dimethyl sulfoxide gel on endotoxin-induced synovitis in horses.
OBJECTIVE
To evaluate the effect of topically applied dimethylsulfoxide (DMSO) on lipopolysaccharide (LPS)-induced synovitis in the mid-carpal joint.


METHODS
6 sound, healthy, adult horses (12 carpi).


METHODS
In a double-blinded, crossover, paired study with a 1-week washout period, mid-carpal joints were allocated to group 1 (DMSO, n = 6) or group 2 (control, n = 6). Each joint was injected with 1.3 ml (0.0125 ng/dl) of LPS to induce synovitis. For group-1 joints, DMSO gel (15 g; 90%) was applied after injection of LPS and at 12-hour intervals for 60 hours. Joints of group 2 received LPS, but not DMSO gel. All horses were evaluated by serial lameness examinations and synovial fluid analyses (total and differential WBC count and total protein concentration) at 12-hour intervals for 60 hours after LPS injection. Plasma and synovial fluid were obtained at baseline and 36 hours to document presence of DMSO.


RESULTS
Mean WBC concentration was significantly (P < 0.05) lower in group-1, compared with group-2 joints, at 24 hours and had a trend to be lower at 36 hours. Mean total neutrophil count was significantly lower in group-1, compared with group-2 joints at 24 hours. In group-1 joints, DMSO was detected by use of gas chromatography in the synovial fluid of 5 of 6 joints and in plasma from 1 of 6 horses.


CONCLUSIONS
Topically applied DMSO penetrated into synovial fluid in sufficient quantities to be detected and to decrease joint inflammation.
Smith
G
G
Department of Orthopedic Surgery, College of Medicine, The Ohio State University, Columbus 43210, USA.
Bertone
A L
AL
Kaeding
C
C
Simmons
E J
EJ
Apostoles
S
S
D000287:Administration, Topical; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004121:Dimethyl Sulfoxide / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*; D004311:Double-Blind Method; D005782:Gels; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D007794:Lameness, Animal / Q000188:drug therapy / Q000209:etiology; D007958:Leukocyte Count / Q000662:veterinary; D008070:Lipopolysaccharides; D013582:Synovial Fluid / Q000166:cytology; D013585:Synovitis / Q000139:chemically induced / Q000150:complications / Q000188:drug therapy / Q000662:veterinary*
D000893:Anti-Inflammatory Agents; D005782:Gels; D008070:Lipopolysaccharides; D004121:Dimethyl Sulfoxide