Analysis of lactate concentrations in canine synovial fluid

To report synovial fluid lactate concentrations in normal and pathological canine joints.

Controlled, prospective study.

Lactate was measured in synovial fluid using a hand-held meter and the rest of the fluid was sent to a commercial laboratory for analysis. Samples were divided into four groups; group 1: control, group 2: osteoarthritis, group 3: immune-mediated inflammatory arthritis, and group 4: septic arthritis. Statistical analysis was performed to compare lactate concentrations between the four groups and to examine the predictive value of lactate in the diagnosis of septic arthritis. A correlation was sought between synovial fluid lactate and synovial fluid total nucleated cell count and total protein.

Seventy-four samples were investigated from 55 dogs. Statistical analysis found that lactate concentrations were significantly higher in the septic arthritis group than in each of the other three groups. No significant correlation could be found between synovial fluid lactate concentrations and synovial fluid total nucleated cell count or synovial fluid total protein. Lactate concentration was found to be a useful predictor of septic arthritis, with a low concentration pointing towards exclusion rather than a high concentration to the diagnosis of septic arthritis.

Synovial fluid lactate concentration is not a good marker for osteoarthritis or immune-mediated inflammatory arthritis, but it is significantly increased in septic arthritis and could help the clinician in ruling out this condition in a quick and cost-effective way.