Effect of Rest between Sequential Treatments of Local Anaesthetic and Corticosteroid on Inflamed Equine Articular Tissues

Introduction: During equine lameness investigation, intra-articular administration of local anaesthetic followed by a corticosteroid is common for diagnosis and treatment of osteoarthritis (OA). Anecdotally, veterinarians are advised to separate diagnosis and treatment to allow recovery of articular tissues, however, no scientific evidence supports this need for rest.

Materials and Methods: Synovium and osteochondral explants were harvested from six stifles. After 48 hours of co-culture, with the exception of the unstimulated control group, explants were stimulated with 10 µg/ml recombinant equine interleukin- 1β (IL-1β) and 10 µg/mL tumour necrosis factor-α (TNF-α). After 48 hours, explants were treated accordingly: unstimulated control, stimulated control, TA (10–6 M), MH (4.4 mg/mL) and TA + MH (concurrent). An additional group was treated with MH and, 6 days later, was then treated with TA (delayed). Media were replenished and analysed every 3 days for 9 days total. ELISA analyses for markers of articular tissue cytotoxicity (lactate dehydrogenase, LDH), inflammatory proteins (prostaglandin E2, PGE2), and proteins responsible or indicative for matrix degradation (matrix metalloproteinase 13, MMP-13 and dimethyl methylene blue assay, DMMB) were performed and data analysed with two-way measures ANOVA or mixed-effects models with Tukey's multiple comparisons.

Results: There were no differences in LDH, PGE2, DMMB, and MMP-13 between delayed and concurrent groups at any time point.

Discussion/Conclusion: This in vitro model found that a 6-day convalescence period between intra-articular administration of MH and TA does not enhance equine joint cell viability, decrease inflammation or matrix degradation; concurrent diagnosis and treatment may be more optimal in equine OA.

Acknowledgements: This work was funded by a surgeon-in-training grant from the American College of Veterinary Surgeons (ACVS).

Publication History

Article published online:
26 October 2022