Retrospective study of infection rate in canine mastectomies without associated antibiotic prophylaxis

Sammanfattning: Peri-operative antibiotics are often used by both veterinarians and physicians to prevent and treat surgical site infections (SSI). According to international guidelines, antibiotic prophylaxis is only required when it has been proven to be clinically necessary. Surgeries with no indication for prophylactic treatment with antibiotics include routine procedures such as cutaneous and superficial soft tissue surgeries and clean abdominal procedures. The risk for developing SSI depends not only on external factors such as contamination of the surgical area but also on the patient’s health status and possible concurrent diseases such as e.g. diabetes. Mammary tumours are the most common type of tumour to afflict female dogs. Thus, mastectomy is a common procedure and, in most cases, the gold standard for treatment. Depending on the size, location and invasiveness of the tumour, or tumours, different surgical approaches are available. Mastectomy is usually a clean surgery. However, it can be a large reconstructive surgery due to the necessity to remove extensive amounts of tissue to achieve safety margins. Therefore, this procedure can have an increased risk for complications. According to the literature, SSI rates in clean surgeries range between 0-6%. In the majority of the studies referred to, patients submitted for clean surgical procedures receive pre-operative antibiotics. This makes comparison of SSI rates unreliable. Moreover, to the best of the authors knowledge, there are no prior studies supporting the use of antibiotics in canine mastectomy. This study included 65 separate surgeries, performed on 59 female dogs. This resulted in 95 separate surgical wounds. The surgeries ranged from lumpectomies to radical mastectomies. Information concerning post-operative complications (i.e. SSI) were obtained from medical records. Patients treated with pre-operative antibiotics and/or cortocosteroids were excluded (n=7). Complications reported were divided into; seroma, infection, suture reaction, dehiscensce/wound rupture and other. The total incidence of complications was 20% (n=19/95), whereas SSI rates was 7.4% (n=7/95). These results were similar to previously observed rates in studies analysing SSI rates in clean, surgical procedures receiving pre-operative antibiotics. In conclusion, this study provides no support for the use of perioperative antibiotics in mastectomy in otherwise healthy dogs.