Equine synovial sepsis rate following intrasynovial injection

This study is important when combined with the recent finding that intraarticular antibiotics, typically aminoglycosides, cause inflammation themselves. The use of prophylactic antibiotics when used concurrently with intraarticular medication must be questioned as a routine practice. According to this paper it did not lower the already low incidence of infection.
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Comparison of equine synovial sepsis rate following intrasynovial injection in ambulatory versus hospital settings
Equine Vet J. 2021 Jun 11.
Authors
Danielle Krause 1 , Lynn M Pezzanite 1 , Gregg M Griffenhagen 1 , Dean Hendrickson 1
Affiliation

1 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, 300 West Drake Road, Fort Collins, Colorado, 80523, USA.

Abstract

Background: Frequency of synovial sepsis in horses following intrasynovial injection has been reported, but not compared with respect to environment in which the injection was performed.

Objectives: To describe occurrence of synovial sepsis following intrasynovial injections performed in ambulatory versus hospital settings.

Study design: Retrospective cohort study.

Methods: Records from Colorado State University were evaluated (2014-2018) and horses receiving intrasynovial injections 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=0.2) or without antibiotics (p=0.7) did not alter 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.

Keywords: ambulatory; horse; hospital; iatrogenic; intrasynovial medication; synovial sepsis.