Prevalence and risk factors for surgical site infection following equine colic surgery at the Onderstepoort Veterinary Academic Hospital, South Africa from 2013 to 2021

Abstract

Surgical site infection (SSI) is a significant cause of postoperative morbidity following exploratory laparotomy as a means of investigation and treatment for equine colic. If risk factors can be identified for the development of surgical site infection, they could be mitigated and morbidity as a result may thus be reduced. Although the prevalence and risk factors of SSI infection after exploratory laparotomy for equine colic have been identified worldwide, these factors have not been established in a referral hospital in South Africa. The objectives of this research study are to report the prevalence of SSI following colic surgery in horses at the Onderstepoort Veterinary Academic Hospital (OVAH), Equine hospital, University of Pretoria, South Africa, and to identify possible pre-, intra-, and postoperative risk factors for the development of SSI. Data was collected, and analysed retrospectively from the clinical records of all the horses that underwent exploratory laparotomy at the OVAH, for the investigation and treatment of colic over a period of 8 years from April 2013 to April 2021. Follow-up telephonic and/or email communication was performed with owners in all horses discharged after exploratory laparotomy. The association between the occurrence of SSI and each potential risk factor was assessed in a univariate analysis model. Only variables found to be significant in the univariate analyses were included for further analysis. The remaining pairs of variables were checked for collinearity, after which a final assessment was performed using a multivariable logistic regression model. From the clinical records of 144 horses that underwent colic surgery, it was found that 119 (82.6%) horses survived until discharge and 25 (17.4%) were euthanised. Of the 144 horses, 39 (27.1%) suffered surgical site infection. Multivariable analysis showed that horses which had no abdominal bandage applied following colic surgery were significantly more likely to acquire SSI than horses with an abdominal bandage placed postoperatively. The odds of horses developing SSI decreased with an increase in preoperative total protein values. The placement of a hernia belt was determined to be a significant postoperative risk factor for SSI. These findings assist with identifying factors that may increase the risk for horses developing SSI following exploratory laparotomy and furthering development of preventative strategies.