Prophylactic antimicrobial therapy or preoperative administration of antimicrobial drugs is a means of helping to avoid surgical site infections. Despite its advantage in some dogs, the misuse in other dogs can lead to the development of (multi-)resistant bacteria, which is an emerging threat not only in people but also more and more in veterinary medicine.
Risk Factors for the Development of Surgical Site Infections
In order to decide which patient will benefit from prophylactic antimicrobial therapy, risk factors for the development of a surgical site infection have to be weighed against the risk of contributing to the development of antimicrobial drug resistance. Multiple risk factors have been described in dogs and cats. Risk factors can be divided into patient-related, environmental-related, and treatment-related risk factors on the one hand and into pre-operative, perioperative, intraoperative, and postoperative risk factors on the other hand. Immunocompromised patients and patients with endocrinopathies are at increased risk for developing surgical site infections. Other patient-related risk factors include the presence of subaortic stenosis and carriers of multi-resistant bacteria.
Environmental-related factors comprise, amongst others, presurgical preparation both of the patient and surgeon(s) and the use of clean, sterile, and well-maintained surgical equipment. Treatment-related factors include the placement of implants, drains, and the method of skin closure. Both the method and timing of clipping patients are important preoperative risk factors. Perioperative risk factors comprise the duration of anaesthesia and surgery, and intra-operative risk factors include the type of surgery, development of intraoperative hypotension, and absence of excellent surgical technique with strict adherence to Halsted principles. Finally, the length of the hospital stay and automutilation are postoperative risk factors. Taking all risk factors into account, the risk for the development of a surgical site infection can be defined for each individual patient.
Type(s) of Prophylactic Antimicrobial Drug(s) to Be Administered
If, based on the risk assessment for the development of a surgical site infection, a patient benefits from prophylactic antimicrobial drugs, the optimal antimicrobial drug should be determined. The type(s) of antimicrobial drug(s) that should be administered depend(s) on the organ system that will be operated on. Knowledge of the most commonly identified bacteria per organ system is of utmost importance.
Posology of Prophylactic Drugs
Besides the administration of the correct antimicrobial drug, also the route, dose, timing of first administration, frequency of repeating the administration during surgery, and duration of administration postoperatively are important to help to reduce the development of (multi-)resistant bacteria. In conclusion, an individual assessment is always needed to outweigh the advantages and disadvantages of the use of prophylactic antimicrobial drugs. If possible, prophylactic antimicrobials should be omitted to help reduce antimicrobial (multi-)resistance formation. Importantly, antimicrobial prophylaxis can never replace aseptic surgical techniques with correct tissue handling.
References
1. Nicholson M, Beal M, Shofer F, et al. Epidemiologic evaluation of postoperative wound infection in clean-contaminated wounds: a retrospective study of 239 dogs and cats. Vet Surg. 2002;31:588–581.
2. Espinel-Rupérez J, Martín-Ríos MD, Salazar V, et al. Incidence of surgical site infection in dogs undergoing soft tissue surgery: risk factors and economic impact. Vet Rec Open. 2019:e000233.
3. Muna WF, Ferrans VJ, Pierce JE, et al. Discrete subaortic stenosis in Newfoundland dogs: association of infective endocarditis. Am J Cardiol. 1978;41:746–754.
4. Piirainen K, Grönthal T, Mölsä S, et al. Are postoperative antimicrobials necessary to maintain an acceptable SSI rate in canine clean orthopaedic and neurosurgeries? Vet Surg. 2019;48:658.
5. Verwilghen D, Singh A. Fighting surgical site infections in small animals. Vet Clin North Am Small Anim Pract. 2015;45:243–276.
6. Turk R, Singh A, Weese JS. Prospective surgical site infection surveillance in dogs. Vet Surg. 2015;44:2–8.
7. Eugster S, Schawalder P, Gaschen F, et al. A prospective study of postoperative surgical site infections in dogs and cats. Vet Surg. 2004;33:542–550.
8. Frey TN, Hoelzler MG, Scavelli TD, et al. Risk factors for surgical site infection-inflammation in dogs undergoing surgery for rupture of the cranial cruciate ligament: 902 cases (2005–2006). J Am Vet Med Assoc. 2010;236:88–94.
9. Mayhew PD, Freeman L, Kwan T, et al. Comparison of surgical site infection rates in clean and clean-contaminated wounds in dogs and cats after minimally invasive versus open surgery: 179 cases (2007–2008). J Am Vet Med Assoc. 2012;240:193–198.
10. Brown DC, Conzemius MG, Shofer F, et al. Epidemiologic evaluation of postoperative wound infections in dogs and cats. J Am Vet Med Assoc. 1997;210:1302–1306.
11. Ruple-Czerniak A, Aceto HW, Bender JB, et al. Using syndromic surveillance to estimate baseline rates for healthcare-associated infections in critical care units of small animal referral hospitals. J Vet Intern Med. 2013;27:1392–1399.
12. Aiken MJ, Hughes TK, Abercromby RH, et al. Prospective, randomized comparison of the effect of two antimicrobial regimes on surgical site infection rate in dogs undergoing orthopaedic implant surgery. Vet Surg. 2015;44:661–667.