Introduction: Intra-articular botulinum toxin A (IA BoNT A) has produced pain relief in osteoarthritic dogs and human patients without clinical adverse effects. However, its effects on intra-articular tissues have not been studied. Our purpose was to investigate the effects of IA BoNT A on joint cartilage and synovium. The hypothesis was that the toxin would not cause adverse effects on the intra-articular tissues. Material and Methods: Six healthy laboratory beagle dogs assigned for euthanasia due to other reasons were studied in a placebo-controlled, blinded, randomized trial approved by the Committee of Experimental Animals (ESAVI-2010-04178/Ym-23). Dogs were randomized to receive an injection of 30IU BoNT A (Botox®; Allergan Pharmaceuticals Ireland) into the right or left stifle joint. Placebo (0.9% saline) was injected into the contralateral joint. Synovial fluid (SF) was analyzed before and 2,4,8, and 12 weeks after the IA injections. Dogs were euthanized after 12 weeks. The stifle joints were macroscopically evaluated. Biopsies were taken from the articular cartilage and synovium. The histopathological evaluation of the cartilage and synovium biopsies was performed according to the OARSI Histopathology Initiative by two independent, blinded reviewers. The cartilage was evaluated by scoring its structural integrity and chondrocyte pathology. The synovium was evaluated by scoring the number of lining cell layers and the presence of villous hyperplasia and inflammatory cell infiltrates. The obtained scores were used for statistical analysis. Repeated measures ANOVA, logistic regression analysis, and cumulative logit-model were used in the statistical analysis. Statistical significance level was set to P < 0.05. Results: SF cell count was in the reference range in all samples analyzed. There was no statistically significant difference in the SF neutrophil percentage (P = 0.960) between the BoNT A and placebo injected joints during the study. No pathological changes were detected in the macroscopical evaluation of the stifle joints. No statistically significant difference was detected in the scores for cartilage and synovial structure and synovial inflammatory cell infiltrates between the BoNT A and placebo injected joints. Conclusion: Our results suggest that IA BoNT A does not have degenerative or inflammatory effects on joint cartilage or synovium.
Original languageEnglish
Publication statusPublished - 13 Jul 2017
EventECVS Annual Scientific Meeting - Edinburgh, United Kingdom
Duration: 13 Jul 201715 Jul 2017


ConferenceECVS Annual Scientific Meeting
CountryUnited Kingdom

Fields of Science

  • 413 Veterinary science

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