Equine Specialty Intern Colorado State University Fort Collins, Colorado
The Effect of Prophylactic Antimicrobial Delivery on Postanesthetic Fever in Horses Undergoing Elective Orthopedic MRI: Retrospective Analysis of 791 MRI Studies. Hoblick SC1, McCarrel TM2, Denagamage TD2, Morton AJ2. 1Oakridge Equine Hospital, Edmond, OK; 2University of Florida, College of Veterinary Medicine, Gainesville, FL.
The incidence of infection is critical to justify antimicrobial prophylaxis for elective procedures, however this information as well as efficacy of antimicrobial prophylaxis for reducing postanesthetic fever is lacking for horses undergoing magnetic resonance imaging (MRI). We hypothesize that prophylactic antimicrobials would decrease the incidence of postanesthetic fever. This retrospective cohort included 791 elective orthopedic MRI in systemically healthy horses between June 2006 and March 2020 that recovered from general anesthesia, and did not undergo surgery or intensive medical therapy soon after recovery. Potential factors associated with postanesthetic fever were evaluated using a chi-square test. Factors identified as significant in univariate logistic regression analyses were evaluated in a multivariate logistic regression model. Patient signalment, travel time, preanesthetic bloodwork abnormalities, perioperative nonsteroidal anti-inflammatories, and anesthesia time were all evaluated for association with postanesthetic fever. Of 791 studies, 44 (5.6%) developed a postanesthetic fever. Horses that received prophylactic antimicrobials were 3.7 (95% CI = 1.87–7.31) times more likely to develop a postanesthetic fever than those that did not receive antimicrobials (P = 0.0002). Age was the only confounding factor (OR 0.89, 95% CI = 0.81–0.97, P = 0.0115) identified in the multivariate model with fever reduced with increasing age. While fever may indicate infection, the majority of early postanesthetic fevers were self-limiting with no identifiable cause. Limitations of this study pertain to retrospective analysis including nonrandomized patient selection and incomplete data records. The use of prophylactic antimicrobials to reduce the risk of postanesthetic fever for elective MRI is not supported by this study.