Abstract
Objective—To compare gentamicin concentrations achieved in synovial fluid and joint tissues during IV administration and continuous intra-articular (IA) infusion of the tarsocrural joint in horses.
Animals—18 horses with clinically normal tarsocrural joints.
Procedure—Horses were assigned to 3 groups (6 horses/group) and administered gentamicin (6.6 mg/kg, IV, q 24 h for 4 days; group 1), a continuous IA infusion of gentamicin into the tarsocrural joint (50 mg/h for 73 hours; group 2), or both treatments (group 3). Serum, synovial fluid, and joint tissue samples were collected for measurement of gentamicin at various time points during and 73 hours after initiation of treatment. Gentamicin concentrations were compared by use of a Kruskal-Wallis ANOVA.
Results—At 73 hours, mean ± SE gentamicin concentrations in synovial fluid, synovial membrane, joint capsule, subchondral bone, and collateral ligament of group 1 horses were 11.5 ± 1.5 μg/mL, 21.1 ± 3.0 μg/g, 17.1 ± 1.4 μg/g, 9.8 ± 2.0 μg/g, and 5.9 ± 0.7 μg/g, respectively. Corresponding concentrations in group 2 horses were 458.7 ± 130.3 μg/mL, 496.8 ± 126.5 μg/g, 128.5 ± 74.2 μg/g, 99.4 ± 47.3 μg/g, and 13.5 ± 7.6 μg/g, respectively. Gentamicin concentrations in synovial fluid, synovial membrane, and joint capsule of group 1 horses were significantly lower than concentrations in those samples for horses in groups 2 and 3.
Conclusions and Clinical Relevance—Continuous IA infusion of gentamicin achieves higher drug concentrations in joint tissues of normal tarsocrural joints of horses, compared with concentrations after IV administration.
