Comparison of equine synovial sepsis rate following intrasynovial injection in ambulatory versus hospital settings.

BACKGROUND: Frequency of synovial sepsis in horses following intrasynovial injection has been reported, but not compared with respect to the environment in which the injection was performed. OBJECTIVES: To describe occurrence of synovial sepsis following intrasynovial injections performed in ambulatory vs hospital settings. STUDY DESIGN: Retrospective cohort study. METHODS: Records from the Colorado State University were evaluated (2014-2018) and horses receiving intrasynovial injections were identified. Patients presenting for septic synovial structures were excluded. Patient signalment, primary supervising service, medications injected, location (field/hospital), whether synovial sepsis resulted, and at what time sepsis was recognised were recorded. Logistic regression was used to estimate the contributions of covariates to the occurrence of synovial sepsis following injection. RESULTS: During the study period, 3866 intrasynovial injections were performed in 1112 horses during 1623 sessions, with 643/1623 sessions performed in the field. The most frequently used medications were hyaluronate (846/1623, 52.1%), triamcinolone acetonide (780 /1623, 48.1%) and amikacin sulfate (684/1623, 42.1%). Four horses developed synovial sepsis (0.2% sessions, 0.1% synovial structures); 3/4 were injected in the field, 2/4 received antibiotics with the injection. The frequency of septic synovitis was 10.4 cases per 10 000 injections, or 1 in 967 injections. All horses recovered following synovial lavage and antibiotic therapy. Performing injections in the field (P = .2) or without antibiotics (P = .7) did not alter the risk of synovial sepsis. MAIN LIMITATIONS: Limitations include the retrospective nature of data collection and low rate of infection overall, which prohibited evaluation of individual medication regimes as factors associated with resultant infection. CONCLUSIONS: The frequency of synovial sepsis in this population of horses was not higher when injections were performed in the field or without concurrent antibiotic administration. These data may help to inform practitioners and clients regarding the relative potential risk of complications following intrasynovial medication in different environmental settings.

Synovial sepsis is rare following intrasynovial medication in equine ambulatory practice.

BACKGROUND: There are few observational studies regarding the potentially serious complication of synovial sepsis following intrasynovial medication in general equine practice. Quantification of risk is fundamental to fully inform decision-making and owner consent prior to undertaking procedures. OBJECTIVES: To describe the occurrence of synovial sepsis following intrasynovial injections in a large ambulatory equine practice between 2006-2011. STUDY DESIGN: Retrospective cohort study. METHODS: Medication records were cross-referenced against synovial cytology submissions and hospital admissions for synovial sepsis. The occurrence of synovial sepsis within strata of interest, including horse age, sex and product used were described as proportions with corresponding 95% confidence intervals, and measures of attributable risks. RESULTS: In the study period, 9456 intrasynovial medications were performed in 4331 sessions. The most frequently used medications were: corticosteroids (3869/4331, 89.3% [95% CI 88.4, 90.3%]), hyaluronate (3617/4331, 83.5% [95% CI 82.4, 84.6%]) and amikacin sulphate (4044/4331, 93.4% [95% CI 92.6, 94.1%]). Overall four horses developed post medication synovial sepsis (0.04% [95% CI 0.0, 0.08%] of all medications), two of these cases were given polysulphated glycosaminoglycans and hyaluronate (2/14, 14.3% [95% CI 0.0, 32.6%]), two were given triamcinolone acetonide (2/3592, 0.1% [95% CI 0.0, 0.1%]), and hyaluronate (2/3617, 0.06% [95% CI 0.0, 0.1%]). One of these cases had received concurrent medication with amikacin sulphate (1/4044, 0.02% [95% CI 0.0, 0.1%]). All four cases returned to racing following joint lavage. MAIN LIMITATIONS: Due to the low frequency of cases multivariable statistical analysis was not performed. Although the study was conducted in an ambulatory setting, the population included a high number of racehorses, limiting application to the general horse population. CONCLUSIONS: The frequency of synovial sepsis in this population of horses was 0.04%. These data may be helpful in informing clients regarding the potential risks of adverse complications resulting from intrasynovial medication.